Kyon: Big Damn Hero/WMG

Jossed or confirmed guesses are in their own folder at the end of the list (spoilers are unavoidable there, so open it at your own risk).

The authors of the title opening quotes are not all Kyon.
In fact, only one of the named authors is him; each character only has a single name to sign their books.

Kyon is the author of all the how-to-be-a-hero books, and Yuki wrote the poetry.
Anything else is probably written by someone else.
 * This is pretty much confirmed because Tsuruya Kenshiro slips up and says Considering the author is Tadamichi Kyousuke, it seems pretty likely.

The author of one of the books is TK because of the Arranged Marriage situation.
To confuse us or to make it more noticeable.

The PDA is going to evolve so that it can change the physical properties of clothing.
Not just changing what's visible, it will actually make clothing change shape to match other clothing. Of course, this wouldn't work for the coat, since that's protected, but that could just hover in the strange dimension Hanyuu occupies. Which would make it a lot less awkward to have on hand than mere camouflage.

The authors of each chapter preface's Fictional Document are members of the (eventually expanded) SOS Brigade, and perhaps other characters.

 * Theory #1 (by User:Marq FJA): "Tadamichi Kyousuke" not only sounds like Kyon, but ; the ones labelled '"Cover" -- Author Unknown' sounds highly similar to a post-"Masquerade Reveal" Haruhi; the ones labelled '"[CLASSIFIED]" -- Paraea Mons T.E.S.A. Dataplume' are painfully obvious to be by Future!Mikuru; "T.H." is almost certainly Tsuruya (the girl, not her father); '"Snow, Verses: A Compilation"' is also obviously done by Yuki; the "Clan Annals" are vague at best, but as they're done by "Tsu-Oyabun #108", it's seems safe to assume for now that the author is the 108th Oyabun of the Tsuruya Yakuza, though it remains unknown whether it's a future Tsuruya Haruka, her father, or a more distant Tsuruya descendant (possibly through Kyon?). The only one unaccounted for is Koizumi.
 * Cover seems more like something Kyon would write, could you imagine Haruhi hiding from anything?
 * It's more of a process of elimination. Besides, Haruhi would have the most practice maintaining a masquerade. She's organizing a Tenchi Solution, while keeping Kyon's Genre Savvy nose out of it, and for a short time, had to control her incredibly sensitive powers. Also, Current!Mikuru is going to go back to the future and age into her future self, so that should give her time to write her articles.
 * But Kyon has helped maintain a masquerade as well: keeping Haruhi in the dark about her powers for close to a whole year. And keeping Kyon in the dark about the Tenchi Solution is hardly difficult... Oblivious to Love, after all. That and the whole Yakuza thing ought to count for something in Kyon's favour. Also, how do the sensitivity of Haruhi's powers have anything to do with a masquerade?
 * User:Marq FJA: He's referring to how she applied Memory Gambit on herself to, ultimately, give limited Mind Over Matter, allowing her to use her Reality Warping without accidentally causing a disaster, and in the same time give herself an outlet to vent her frustrations and boredom; in other words, she's pulling a masquerade on herself, and it's working. As for Cover, the "tone" of the passages looks closer to Haruhi's Genki Girl attitude than Kyon's Deadpan Snarker. And even if she has nothing to hide from, it's not like pulling a Masquerade on her is an easy job , so she'd be in an ideal position to give pointers in that regard by setting herself as an example of someone who is smart, Genre Savvy, inquisitive and suspicious enough to make doing so a challenging feat.
 * A Memory Gambit doesn't equal a Masquerade, if it was a masquerade, wouldn't there be a fear that it could be broken and someone else could find out? There's nothing like that in this case, the only person who has any idea what has happened is Kyon. Does that really sound like Haruhi to you? It may not be completely sarcastic, but it still seems cynical enough to be Kyon, I think. And keeping Haruhi in the dark about the Masquerade was easy. Kyon did tell her about it and she refused to believe. Which meant all they needed to do was stop her seeing anything supernatural. And she still failed to see through it when the cherry trees bloomed in autumn and the pigeons changed colour. Plus she automatically accepted that Yuki was a ventriloquist rather than Shamisen talking.
 * The Tsu-Oyabun is the actual Haruka Tsuruya, not a future self, not her father. Note in Gearing Up arc-1, there's a dated entry (May 11th, 2011; Wednesday ): Tsuruya's father doesn't know Kyon so he can't really know he may not be okay with revenge. And while by this point she isn't the family head Kyon says she's his Oyabun in Hinamizawa a week earlier.
 * Alternatively, T.K and T.H are Kanae and Haruhi, respectively, after a Tenchi Solution and some serious Character Development - note that T.K. writes a book titled "Mirror, Mirror" which is all about how to stop running away, while T.H.'s excerpts are about being an effective leader. The subjects of the books imply that T.K. was running away from her problems for a very long time and that T.H. was some sort of leader herself - which fits with Kanae-chan the slider and Haruhi the brigade-chief. And, of course, the title "Mirror, Mirror" practically screams slider - and apparently "Kanae" can mean "reflection". Naturally, Polyamory is frowned upon, so they can't introduce themselves as Tadamichi Haruhi and Kanae, hence the initials. This leaves "Author Unknown" of "Cover" open for Koizumi to write - which is a book on, among other things, how to pretend to be someone you're not - which Koizumi has openly admitted he's been doing for years.
 * Though T.H. could just as easily be Tsuruya, and Cover suggests someone a lot less polite than Koizumi.
 * Unless the real Koizumi, the one that we and the cast don't get to see, is much less polite-talking, or is enjoying the freedom granted by his pseudonym a little too much.
 * Well, he did claim he was a bit of a shallow, petty, Manipulative Bastard before esper-hood, so "less polite-talking" might not be that much of a stretch. And who, besides Kyon, was the most actively involved in enforcing The Masquerade? Admittedly, Haruhi and Tsuruya have similar full-power-right-from-the-start personalities and both are in leadership roles, so it's hard to tell which is which, but I'm leaning towards Haruhi for symmetry if nothing else. Also found this "Mirror, Mirror" quote - "At least, you'd have to find one really solid ally, and then make sure you're there for them enough so that they can be there for you too!" - which really sounds like Kanae and her Sempai.
 * Also note the entry for Meaningful Name: one of possible's meanings for Kanae is reflection, linking it with "Mirror, Mirror".
 * We now have official confirmation from Chapter 28 that "Tsu-Oyabun #108" is Haruka Tsuruya, as well as de facto confirmation that "Tadamichi Kyousuke" is Kyon.
 * If chapter 31's excerpt is anything to go by, Koizumi DID write Cover. It says never to let people overestimate your abilities... when for the first part of the chapter he was convinced he could do nothing useful in a fight. When it was necessary.
 * Alternatively, Cover is a collaboration between every member of the brigade. Enough perspectives on a masquerade to ensure the advice is reliable and it would also explain why there's no author known. There'd be six at the minimum.
 * "Tending the Flame" seems to be Sasaki's work.
 * Here is a list of all of Fictional Documents seen so far and some conclusions me and some fellow tropes have drawn.
 * "Practical Heroism and You: Awareness" "Roll With the Punches" "Clearing the Event Horizon: How Close is Too Close?" "The Last Resort: Violence and You" "Training and You: the Eternal Nightmare" all written by one Tadamichi Kyousuke. this Tadamichi Kyousuke sounds exactly like Kyon and lets face it, but now the fact that Kyon is Tadamichi Kyousuke has been practically confirmed with everything but the Word of God
 * "File K:3453.3.1/2011.4.17" "File K:3419.8.19/2011.4.21" "File K:3453.3.5/2011.4.22" "File K:3419.8.19/2011.4.25" "File K:3419.8.19/2011.5.20" all from "[CLASSIFIED]" -- Paraea Mons T.E.S.A. Dataplume. Given the language and wording involved it make a lot of sense that the person recording this is (Big or Small or Both)Asahina.
 * An additional conclusion can be drawn. If we assume that the first string of numbers is the date Up where Asahina if from, the second string is down with the SOS-dan and that they represent the dates the files were recorded on both sides, then it appears that the files are recorded at two time roughly 34 years apart. One possibility is that 3419 is when Asahina first goes back becoming our Small!Asahina and 3453 is when she goes back a second time to interfere with herself, Kyon, and by extension, the rest of the SOS-dan becoming our Big!Asahina
 * "Snow, Verses: A Compilation" -- Committed to record: 2011.4.23, 2011.5.5, 2011.5.18, 2011.5.21, 2011.6.1 sound a lot like a poetic take on Yuki's point of view. Add to that the fact that Yuki roughly translates to snow and the fact that we have seen Yuki messing with a text editor on in the pass, it makes the most sense that she wrote it.
 * "Methods of Victory" by 'T.H.' Is about how to be a effective leader of a wide verity of people and goes at the subject with all the energy we normal see in Haruhi. There is also an implied level of experience in the words, indicating that the writer has been a leader of something literally or metaphorically big in the past
 * "Mirror, Mirror" -- T.K. to barrow from an earlier argument, "Mirror, Mirror" is about how to stop running away and face your problems. The exerts imply that this T.K. was running away from her problems for a quite a while. Among other things it talks about finding one solid friend or ally that you can depend, something Kanae has in spades in her Sempai-kōhai with Kyon. For added impact one of the meanings of Kanae is reflection.
 * "Entry for 5.11.2011" "Entry for 5.16.2011" "Entry for 5.19.2011" "Entry for 6.7.2011" -- Tsu-Oyabun # 108" "[Undecipherable]" Recovered From Primary T.E.S.A. Archive. This one will be rather short as that in chapter 28 it was outright declaried that Tsuruya Haruka is the 108 Oyabun of the Tsuruya family.
 * "Cover" -- Author Unknown. My Chronies and I agree with earlier arguments. after reading the books and seeing the sheer level of snark Koizumi displays when using his power and thus revealing his true self plus the discussions on how to be someone you are not, something he had to do to join the SOS-dan in the beginning, make it hard to see the book being writen be someone else.
 * "Adaptation" -- LP-TK:AR Datastream Segment and "Perspective" -- LP-TK:SK Memetic String. While we cannot figure out what LP might be, my corner has come to several conclusions
 * TK is Tadamichi Kyousuke or Kyon again because, let's face it, Kyon is at the center of a lot of things.
 * AR is Asakura Ryouko. The LP-TK:AR Datastream Segment entry uses a lot of Data entity phrases making the argument stronger.
 * SK is most likely Suou Kuyou. the LP-TK:SK Memetic String talks about things from the point of view we have only seen Kuyou use.
 * "Tending the Flame" Sounds a lot like Sasaki. It deconstructs the idea of faith, saying that it might be just a odd evolutionary quirk that serves no purpose, while at the same time suggesting it might be worth it. Now is it just me, or has Sasaki recently begun believing in something that she had previously deconstructed?

Mikuru is descended from Miyoko.
"The one with longer hair kept telling Miyoko she was very pretty, and would grow into a real beauty herself."
 * They were both able to touch the genetically locked device, so they must be directly related. Either Mikuru is Miyoko's descendant or Miyoko becomes Mikuru in the future.
 * Unlikely, just due to the fact that Mikuru and Miyoko met, and Mikuru seemed to have no reaction. And Mikuru would still know if it was her. . . and their complete opposite views in the ability to withstand bloodshed initially likely refutes anything without sufficient trama occuring. So unless the future (which also seems to be within twenty years) causes Mikuru to be orphaned from Miyoko as a child, then direct descent is likely improbable. Though if she was related to Miyoko indirectly, from the run away lovers, it would be likely Mikuru would have had no idea who Miyoko is. And Mikuru would have recognized Fujiwara as a brother, so if we assume one of the people ran away after becoming or getting pregnant from their "lover" I would assume that they could be related through mother or father.
 * Actually, Mikuru's reaction to meeting Miyoko (in chapter 19) is interesting, and taken with a bit of literalism, could be foreknowledge. Miyoko being a famously beautiful ancestress isn't out of the question.

In the future, Kyon is stupidly famous.
""Kowa-Keigo-Kyon, eh? So you really do have mystic powers.""
 * In addition to the So You Want To Be A Hero type books, there's this T.E.S.A. excerpt where (probably) future Mikuru seems to be addressing raw recruits: "No, I will not ask [CLASSIFIED] to autograph anything for you."
 * Kyon seems to be starting to becoming this among the Yakuza circles, as hinted to by Fujiya in The Calm Before The Storm Arc 1...

Kyon will gain a Healing Factor.
Eventually Haruhi and/or Yuki will get tired of having to be nearby to prevent Kyon dying from whatever he manages to get injured by, resulting in this being used.
 * It doesn't make much sense from a Doylist point of view because it'd make Mikuru's third known training theme (paramedic) obsolete.
 * ... Unless the Healing Factor lacks a certain Required Secondary Power, necessitating that the more severe injuries receive some first-aid treatment before it can heal right (e.g. setting broken bones correctly and keeping them in place). Alternatively, it might consume too much energy/biomass from him without Yuki or Haruhi around, thus maintaining the value of Mikuru's paramedic skills if she and a grievously injured Kyon were isolated from the others.
 * Could also be a Red Herring.

Hanyuu will be granted the ability to change between material and ghost/data at will.
Kyon already aknowledged she lives a lonely existence, with Rika as her only link to the material world before meeting Yuki. He'll ask Haruhi when the SOS Brigade goes to Hinamizawa for the Watanagashi festival/Kyon's birthday. (Haruhi may decide it on her own if she is told Hanyuu's story)

Kyon will get a Power Tattoo.
He is part of the Yakuza, so a tattoo (though probably not one created over the course of years... unless Year Inside, Hour Outside is used) isn't that far-fetched. Given what seems to happen to anything he gains in this fic, it being given some sort of power isn't that unexpected. Possibly tied into the Healing Factor idea mentioned above?

Tokyo will become involved in the story sometime in the future.
I don't know about the rest of you but the Higurashi arc seemed like one giant Big Lipped Alligator Moment to me -- though it was a pleasant one to be certain -- whose only apparent purpose was to get the idea of the Tenchi Solution into Haruhi's head, something that could've been done without a crossover. But I doubt that's all there is to it; I think this is a Chekhov's Crossover. Keiichi and the gang are going to become involved again at some point in the future, probably because Miyuki's investigation is going to bear fruit, and Haruhi's powers are going to catch the attention of someone from Tokyo and a veteran officer in her department... Akasaka.
 * Akasaka Sr. has retired for some time now. He and his daughter Miyuki weren't NPA officers at the same time.
 * Is this mentioned in-fic or in Higurashi? He could've been promoted or reenlisted in the 15+ years since the end of the series. Regardless, if the Higurashi characters come back into the story, there's a good chance they'll do so because the one plot hook that Higurashi completely left hanging gets snagged on Kyon's shirt, Akasaka getting involved would just be a bonus.
 * It's mentioned in Miyuki's introduction to the story, actually. As for going back at Watanagashi, that's bound to happen. Why miss out a festival on someone's birthday from the collection of events? And it seems unlikely anyone's going to listen to Kyon's mother at that point.

Fujiwara is Miyoko's descendant.
She could touch the slider's weapon, and since the last person to touch it was Fujiwara...
 * Alternate theory to above: Fujiwara is the descendant of Kyon's "cousin" and Miyoko's older brother. Since relatives could still touch the weapon freely. Though that doesn't explain why Kyon couldn't touch it originally. . . though he likely wouldn't have known that he is related obliquely to Fujiwara. Which still allows the possibility of Miyoko to be in the harem and Kyon's inability to touch it.

Kanae will become Dark!Kanae after learning that she might have killed hundreds of versions of herself.
After finding out just how many versions of herself she has either permanently destroyed or mind-raped, she will suffer a Heroic BSOD and slide into another world... where she meets the sliders she has been running away from all the time before they had any reason to chase after her. She will then be offered the chance to save all of the versions of herself that suffered because of her actions by stopping the original Kanae - and perpetuating the Stable Time Loop. Because there's no indication that any of the other sliders aged, time-travel is likely to be involved - maybe Fujiwara? Since Kanae's grasp of how bad breaking Stable Time Loops is rather lacking, especially the results of breaking them on an inter-dimensional scale...

This leads on to the following...

Kanae will realise how bad the consequences would be in time to help fight off the alien invasion.
Eventually, the trail will run out right after she left the world the fic takes place in as the invasion starts. After the Heel Face Turn, she might die.

And...

Kanae won't realize how bad the consequences would be.
Either Kyon, Nagato, or Haruhi would have to kill her. And then the alien invasion starts anyway.

Evil!Kanae is the future gestalt amalgamation of every alternate version of Kanae that was/will be "overwritten" by her sliding.
... And she seeks revenge on the good Kanae for the Mind Rape that each of her "precursors" had been subjected to as she "overwrote" them. Perhaps she's deliberately seeking a Spacetime Crash to end her constant suffering of Bad Dreams, I'm Having Soul Pains, etc. caused by the combined Mind Rape experiences... assuming that her current existence isn't constant Mind Rape in and of itself.
 * I had an epiphany a few moments ago and I came to this exact conclusion (Well, the part about Evil!Kanae being made up of all the overwritten Kanaes. the rest... not sure). The entire Kyon: Big Damn Hero fanfiction has, at least, dozens of parallels and references to Higurashi no Naku Koro Ni (Read the very first Fictional Document in the In Medias Res prologue, it makes a reference to the Hate Plague in Higurashi right off the bat). In Higurashi, there is a lot of speculation on who exactly Bernkastel is and how she is related to Rika Furude. The popular theory is that Bernkastel is made up of all of the Rikas who have died and overwritten by the Rika traveling world to world with Hanyuu. Bernkastel, who was made from all the overwritten Rikas also traveled the worlds, making changes to those worlds. If Higurashi!Bernkastel and Umineko!Bernkastel are the same, Then Evil!Kanae being... Well, evil would also be explained.

Fujiwara and Mikuru are siblings or otherwise related.
There's two guesses on this page saying they're descended from Miyoko. Maybe they're siblings, if a bit messed up age-wise due to all the time travel, and radically different ideologies which cause them to never act like it. Also why Fujiwara gives a fake name.
 * They seem to be from different possible futures, so wouldn't it be Alternate Universe Evil Twin?
 * Another possibility is that she is his MOTHER. Fujiwara comments in chapter 53 that Kyon and Mikuru are the two people he absolutely cannot harm, along with some other, vaguer evidence earlier on. There are still a few other possibilities that could explain everything, but it's starting to look like a serious option.

Yuki taught Kyon how to kiss during the training in chapter 10.
It's not specified what training he received. Kyon left it up to Yuki to decide, she smiled about it when Kyon told her she could pick what to teach him, and somehow he's really good at it. Yuki blushed when asked what she does during the training sessions in chapter 13 while Kyon speculated about where she learned how to kiss. Yuki later made the same offer of training to Haruhi later.

Kanae learned Le Parkour from Yuki.
If you are planning to run from somebody, do it right. Vive Kanae, traceuse extraordinaire!

On the same line as the above WMG, Kyon learned Le Parkour from Yuki.
Since Yuki taught Kyon to be as efficient as possible when fighting, she will most probably teach him to move effectively. Especially after she realized that despite all his training, he still can't copy her in Gearing Up Chapter 4, when they broke into the Yamane's place. Later on, in the training sessions, she teaches him how to use gravity manipulation to pull off awesome stunts, like jumping 15 meters in a single jump, then activating his shields and gravity manipulation to send a van careening. "...but [Kyon] had a dogged and steadfast tendency to subdue his opponents in one direction: down."

Skynet is A Red Herring.

 * A painfully obvious one. Seriously, It has the ability to learn, is essentially able to change itself at will without Kyon knowing and is named FREAKING SKYNET. That's like saying your name is Darkdeath Evilman, it's so obvious it's to draw your attention away from something that's actually the threat. Skynet will never betray Kyon.
 * Alternately, it's NOT a Red Herring. All of us Genre Savvy readers are expecting it to be a Red Herring, so naturally we're going to fall victim to the Meta Twist.
 * Alternatively Alternatively it's both. Skynet will betray Kyon to force him into doing something that will end in Skynet getting a more effective virtual avatar in order to better serve Kyon's purposes.
 * Or Skynet will betray Kyon to force him into doing something that will end in Skynet getting a more effective virtual avatar to better serve Kyon's purposes but at that moment in time decides to go on a rampage anyway.
 * Or Skynet may become completely sentient, fall for Kyon, and join in the SOS-dan's Tenchi Solution.

Sasaki is the Anti-Haruhi.
"Such power as her new friends claimed she had - it could only be possessed by a truly infallible being. It was inconceivable that it genuinely existed ... unless, somehow, only she had ever been given that power in the history of man."

Haruhi vs Sasaki - duelling reality warpers, one trying to add Awesome to the world, the other trying to remove it. And they're both in love with Kyon. He's going to end up as the one and only person who gets to choose the course of the entire Universe.

I don't think there's enough Holy Shit Quotient out there to cover this, if I'm right.
 * Book 4 and the entirety of Kyon's actions in this story indicate he would choose Awesome. And isn't the entire point of the Anti-SOS Brigade to get the powers away from Haruhi? That's what Kyouko keeps going on about. I think it's Kyouko.
 * Normally, I would agree. But Sasaki nearly broke him before, without really trying. That sort of history could be hard to overcome...
 * If the Anti-SOS Brigade's goals are to get the powers from Haruhi then Sasaki isn't going to have any powers, is she?
 * Depends how much things deviate from canon - remember, this is the Wild Mass Guessing page, so I don't have to have evidence. And the escape clause on Haruhi's memory gambit is Chekhov's Gun in it's most pure form - Kyon unlocking her power just before Sasaki manages to turn the SOS brigade into normal (if delusional) people would be appropriate as all hell.
 * Sasaki would be using powers to make people with supernatural abilities have no supernatural abilities, including her associates, but without knowledge that she has supernatural abilities and without having done so subconsciously beforehand? And if she DOES have such abilities, wouldn't she be getting rid of them and Haruhi's? In which case we have an Unstoppable Force and an Immovable Object. I think people's heads would start hurting.
 * I was more assuming something along the lines of Sasaki being able to Deconstruct as a weapon - not necessarily destroying someone's more than human abilities, but destroying their belief, effectively removing them. Like what she did to Kyon, without knowing it, in middle school.
 * If that's the case, then I'm guessing both Kyon and Haruhi will be immune to it - Kyon for having had everything Deconstructed before, Haruhi through being a Reality Warper (and possibly Reconstructing everything).
 * So it is Deconstruction (Sasaki) vs. Reconstruction (Haruhi)? That sounds like a TV Tropes theme. In that caso I think the "end" of that conflict will consider the deconstruction and reconstruction is considered a cyclic process.
 * Verified by Suou Kuyou. "She prevents probabilities she will not observe." So Sasaki is basically a Power Nullifier. Fortunately, this only works when she's actually there to observe things.

There's going to be a Big Damn Kiss.
Given the way this story is written... seems inevitable.
 * Some people say this may have already happened. Repeatedly. I'm betting on a Big Damn Wedding officiated by Rika, as the Crowning Moment of Heartwarming.
 * If it has already happened, which girl did he have it with? He has kissed every girl that will be part of the Tenchi Solution (unless more get in on the plan), and has feelings for every one of them. Then again, he'll might temporarily split into several bodies a la Kazuki Shikimori in Maburaho's anime finale, and have a Big Damn Kiss with each girl simultaneously.

The Haruhi substitute in this universe's Lucky Star is Trope-tan.
Lucky Star makes frequent references to Haruhi Suzumiya. In the world of Kyon: Big Damn Hero, Lucky Star is an anime the characters are familiar with. Now, we can't have the K:BDH version of Lucky Star making references to Haruhi Suzumiya because then both universes would explode in pretty recursions, so maybe K:BDH's verison of Lucky Star references Trope-tan instead of Haruhi Suzumiya.

Kanae's previous few universes also had Lucky Star and she watched it.
Why? '"And chocolate coronets!" Kanae added.' That's why.

K:BDH is the result of TV Tropes snapping under all the Haruhi references.
Because you can't go on anywhere on this wiki without bumping into Haruhi, the wiki itself created this fic under the pseudonym Durandall as a means of bringing itself to a state of self-awareness by combining every single trope into one storyline. I shudder to think what will happen once it's done...
 * Instrumentality, Reality Warping, or simply intelligence?
 * Hold it, wouldn't this mean that the author is actually Trope-tan?
 * Maybe Durandall is Trope-tan's brother...

Tadamichi Yuuto (Kyon's Dad) will have a crowning moment of awesome.
It mentions several times that he is an awesome driver, and if Kyon places well he will teach Kyon to drive. I suspect that Yuuto is going to end up being in on The Masquerade. Also - crossover from somewhere?

Miyoko-chan's older cousin ran off with Kyon's older cousin.
They were both their first puppy loves, and both ran off with someone while their families dissaproved.
 * To continue this tree, Miyoko-chan's cousin is Ranma and Kyon's cousin is one of the competing fiancees'

Skynet's AI will develop into a virtual Kyonko.
It learns, after all. Add in constant exposure to Kyon's snark along with all its other users being female, not to mention being created from Asakura's leftover data, and a virtual Kyonko personality seems inevitable. Combine with internet access which could very well lead it to here and there could very well be an appearance to match the personality... if it isn't influenced by Kyon's taste in hairstyles.

The whole reason Kyon's mother is such a Jerkass is because of sexual frustration.
Shion's suggestion taken to eleven.

Kanae will eventually be able to pull a Big Damn Heroes moment with her newly developed
This is based on the cliffhanger at the end of Calm Before the Storm Arc II and the quote at the beginning of said chapter.

Nonoko will become a Magical Girl on the upcoming field trip.
Specifically, she will become Trope-tan. This is why Trope-tan seemed vaguely familiar to Kyon.
 * I thought that it was Mikuru who thought that it seemed familiar, not Kyon. It's mentioned in Gearing Up Arc V, if I'm not mistaken. And I would doubt that Nonoko would become Trope-tan... If anything, it could be just as likely that she could become somewhat akin to a Magical Girl Lyrical Nanoha style of Magical Girl...
 * Add to that Nanoha's high profile on here due to its Troperiffic nature, it does seem more likely.

== Shinobu, the Tsuruya family maid, is in fact the same Shinobu who is the girlfriend of Kyouya Takamachi (who is the hero of Triangle Heart 3, and also the older brother of Nanoha Takamachi...). == This is based on the assumption of the WMG above this one (Nonoko becoming a Magical Girl), and that the events in Triangle Heart 3 (or at least the tropes page for it) would explain why the Tsuruya family isn't bothered that much, if at all, by the unusual.
 * To elaborate, if this WMG was true, it would mean that, among other things, Shinobu may actually be a Japanese Vampire...

Shinobu is Tsuruya's mother or are otherwise related to each other.
She refers to Tsuruya as "Haruka-chan" in a private discussion with Kyon and takes a personal interest in her happiness. She is visibly present and often prominently seated at all important family events. She is aware of Kyon's other relationships and is supportive of them as long as Tsuruya isn't neglected, which implies the situation was explained to her.

Kanae is bisexual.
Seemingly everything she says whilst asleep seems to be, in some way or other, related to perverted dreams. In Calm Before The Storm III she mentioned 'Suzumiya-sempai'.
 * Seemingly confirmed by chapters 50 and 51, with

Everyone Is Bi.
Haruhi will have made one major change to the world in the last Closed Space. It's just that no-one's really worked out what seems different yet. When they do...

Hello Durandall.
We've been expecting you.
 * But didn't we already know he's been watching?
 * But who really is he? He could be any one of us! He could be on this very page! He could be you! He could be me!
 * He could be any of us... He could be all of us... And who's to say that's Durandall is even a he, anyway? Or even... a human...
 * Himself, on his own page.
 * He is watching. And he is laughing at us.

Kuyou will join the harem, leading to better communications between the Data Overmind and the Canopy Domain.
Every other girl who has decided that  has joined. She even mentions that the only one who returned enough spin for her to determine that he might be able to keep the Song from being forced to harmonize with the Noise.

Kyon will eventually face the Combine on their turf and either meet the "One Free Man", or become him.
Because it would be cool and he may have to, in order to save someone, likely Kanae.
 * Could be some timeline issues involved. Assuming that Kanae's home universe is the Half Life universe, she started her sliding soon after the Resonance Cascade, when the Combine invaded Earth. Since the Cascade/Invasion happen in 200X (some sources say 2003, but, like with Suzumiya Haruhi, the year is never confirmed), and the Uprising/Return of Freeman occur in 202X. However, it hasn't been stated how sliding affects time between universes, or how long Kanae has been sliding for. That said, I would love to see Gordon Freeman and K:BDH!Kyon tagteam Nova Prospekt.

Kyon has overestimated how useful a Stable Time Loop is at protecting him from the IDSE.
Fujiwara uses exactly the same reason to claim Kyon can't hurt him until he closes a certain time loop. Kyon scans him with the PDA, explains how he can do whatever he wants to him, then use Tricked Out Time to close the time loop. He doesn't yet acknowledge that the IDSE can get around his Stable Time Loops in exactly the same way. Maybe the IDSE isn't as hostile as they assume?
 * Or maybe the IDSE's actions are restricted by Stable Time Loops in a different way, namely that they're outside of time and don't want to mess with it due to already knowing how things are going to work. Punch Clock Villains restricted by their own nature? Maybe the radical faction is named so because it wants to ignore the time problem?
 * Or they simply have greater access to information. Without the shield of ignorance, a larger proportion of time travel events become predetermined. Essentially, they can't trick out time because they're too smart to fool.

Asakura's attack in the prologue is cause because her faction is bored/upset with not having recent information on the SOS Brigade.
This is based on Asakura's superiors not having updated info on Haruhi by then. The whole "Haruhi Suzumiya" case is a very sensitive matter for the IDSE because it may be the key to the all-important self-evolution they are looking for. Given that Asakura's attack in the Melancholy arc was a serious breach in protocol, potentially damaging the whole mission, all reports on this case are redacted except for very little parts of the Entity, such as Yuki's and Emiri's masters and faction leaders (former in case of Yuki). Either by the possible reaction of Asakura's faction knowing or the lack of real pull of them in the Entity, the Entity at large doesn't want them to know much for risk of another breach on protocol. In that situation Asakura's act looks like an act of protest or because her master simply couldn't wait anymore for a reaction.

Fujiwara is a Continuum Narcissist.
In chapter 36 we have him dropping some fairly obvious Spanner slang, and earlier comments about his freedom of choice versus Asahina-san's predetermination paints him as a Narc and Asahina as a member of the Continuum itself. Based on observed Span range this probably makes them both Ones -with Asahina getting not-infrequent help from her Elder (and building up a very, very busy Yet).
 * If this is true, then Asahina(big) has some serious connections maybe as far Up as Inheritor turf, since Asahina(small) has violated or ignored just about every Maxim at some point or another, including repeated and blatant breakage with the Fourth, and hasn't gotten in trouble for it.
 * Perhaps Asahina(small) is supposed to let the SOS-dan know, because it's Asahina(big)'s way of giving Kyon an Invitation to Dance. Besides, Haruhi does possess Reality Warper powers, who's to say that it isn't a Future!Haruhi that's one of Asahina(big)'s connections. It could even be a Future!SOS-dan that's giving her the leeway or something...
 * That seems likely, actually, considering one of the chapter header excerpts that Asahina(big) wrote (maybe) mentioning no autographs.
 * For additional evidence, Kyon's dropping some Spanner slang too: "Further information is not available here."
 * Let's not forget that the SOS-dan is involved with the creation of time travel because of the Boy with glasses (the same one who is tutored by Haruhi), which is a crucial matter for all the Continuum and a heavily guarded secret. Heck, if this WMG is true, then maybe Kyon actually coined the phrase and his adventures are going to be the concealed guidelines for the Maxims.
 * That Kyon came up with "further information..." himself is confirmed in Chapter 44. It's possible Fujiwara heard it somewhere else, but it doesn't seem likely.
 * Upon further thought, it seems reasonable for Mikuru to have Inheritor backing, given certain assumptions. Suppose the temporal singularity Haruhi created Three Years Ago blocks time travel, but not causality. If there are any Narcissists farther Down than that, the only way to police them would be agents who are already in place (and anyone they recruit), and that's only as long as they stay loyal. That would make smoothing over that singularity a very high priority, probably worth bending a couple of rules.
 * The existence of "a massive temporal fault line" that blocks time travel would frag every spanner Down the temporal singularity too because, by example, many of that spanners are using technology granted by Inheritors. However, if the temporal singularity caused by Haruhi can be deal with like a regular fragging incident (albeit a huge one), then it's going to be solved eventually and the bulk of spanners time-traveling through that point are never going to notice.
 * But the people who fix it will know about it, it should still appear to them to be there while they're trying to fix it, and fixing it would still be a high priority if anyone was trapped Down from it.
 * It's possible that correction already took place. In the 7th novel, just before Yuki restores the world after the events of the 4th book, she says "A large-scale time-quake will be happening shortly," and Asahina(big) tells Kyon "Compared with the one Nagato-san did just now, this one is even more complicated and significant". It seems that there is some support for this in Filler Arc Chapter 4, where Asahina(small) says that a time-quake "only happen when paradoxes are resolved or incurred". Also, if all this is true, then for repairing the temporal singularity was necessary that: Yuki losing control of herself and rewriting reality, destroying and restoring the IDSE, overcomplicated time-travels, creating a whole new parallel universe and Kyon Taking a Level In Badass (yes, very necessary).
 * Based on the line "There was an eerie, mind-wrenching otherness to the space around [Fujiwara], and Kyon was certain he actually felt the reverberations of his retreat...." at the end of Ch. 30 Day at the Beach (one), Kyon has Quick 10 and Shift Sight, which would really help explain why he finds time travel so intuitive.
 * Furthermore, based on that Big Mikuru can span over 100 years and is not mentoring a corner, she is likely Span 4. This implies that she is very likely to either be maneuvering against Antedesertium, or playing the Greatest Game. Either of these has absolutely massive implications in terms of how important Kyon himself is - a Span Four's efforts being so thoroughly dedicated to a single leveller would mean that his Yet is vitally important to the Continuum's very existence. The fact that he gets more effort than the guy who invents time travel indicates his importance is nearly incalculable.
 * Pretty much confirmed by now. As of chapter 53, Fujiwara said that he needed Kyon's help to "slipshank" then corrected it to "deliver a package." the only place I have ever heard the term slipshank use is in the Continuum. Then again Durandall could be reading this and trolling us, I wouldn't put it past him.

Evil!Kanae is Wataru's Empty Shell sister.
And he's chasing the other Kanae to try and get her mind back, and by extension every other Kanae's. Or just revenge, if that's all that's possible.

Wataru is Kanae's half-sister and Takano Miyo's son.
Specifically, from the world shown very, very briefly at the end of Kai. As a result there's exactly one Wataru. This is why Kanae can never remember having any siblings. She's only had a brother in one world of hundreds that she probably didn't spend long in.
 * One correlation of this is that, aside from the possibility of the Evil!Kuyou splitting into hundreds, there are exactly three sliders.

Evil!Kanae is a cyborg and Empty Shell.
Cybernetics Eat Your Soul, only after the soul has been eaten. Possibly to just give her impossible-to-lose weaponry (stealing something from an Empty Shell can't be too hard) or possibly to prevent her from collapsing and going into a coma.
 * Well, considering how the Combine work in Half-Life That's a very strong possibility

Slider!Kanae doesn't overwrite the local Kanae's consciousness.
Instead, she just possesses said person until she slides out again (and the person may be fully aware of what she does while they're possessed, but unable to do anything about it...), only for said person to end up caught by the Combine (and their world being invaded by them) afterwards...
 * Alternately, when Slider!Kanae jumps, she jumps to a locality where the local iteration of Kanae has just slid out of, making sure that typically no one notices the absence.

Kanae is originally from the Half Life Universe.
Rather obvious one, really, but it hasn't technically been confirmed. Her description of what she remembers of the invasion (the sky tearing open, sleek metal things raining down into the cities, and releasing tall spindly creatures) sounds a lot like the Resonance Cascade (Sky tearing open), and the beginning of the Seven Hour War, which included warping Citadels into the hearts of the remaining human cities (the sleek metal things raining down) and unleashing Synths, such as Striders (tall spindly creatures). Wataru more or less confirms that this is the case, given that he calls his masters The Combine, and seems to have some Synths following him around (with the exception of the number of legs they have, the beach sliderbot and the alley sliderbot sound an awful lot like a Strider and Hunter, respectively).

Wataru is NOT in any way related to Kanae.

 * He's just a Villain telling Blatant Lies to attempt to cause Kanae's new allies to turn on her.

Wataru is actually a genderbent version of Kanae, post-Combine invasion.
Since he did declare himself as one of her first victims, and the only people that Slider!Kanae "victimized", albeit unintentionally, are the Kanae of each dimension... "Still.... Haruhi had been a bit melancholy, for some reason asking Kanae if she'd ever remembered any brothers or sisters. Mikuru had thought that the slider's hesitant admission that she had always been an only-child, except for 'Mikuru-onee' had been utterly adorable. Maybe Haruhi wished she weren't an only child?"
 * There's also this to consider...

Kanae does not actually overwrite local Kanae when sliding
Instead, she can only slide in after another slid out, for some reason, or that she PUSHES local Kanae out when sliding in. Which would explain why... "Landing awkwardly in an alley in an unfamiliar city, her clothes torn and face smudged..."

I see no reason why local Kanae would have her this kind of damage on her. Also, "pushing" local Kanae away requires putting local Kanae somewhere, presumably into a different world, "pushing" that world's local Kanae into another world, and so on. There is much Kanaes as alternate worlds, so one of Kanaes has to jump right into the world that the initial Kanae left. Right into Combines' hands.
 * Where does the quote come from?
 * It's from Chapter Three: It Goes to Eleven. As for one of Kanaes jumping into the original world of this particular Kanae, it would only HAVE to happen if there is a non-infinite number of worlds, fitting those prerequisites. If it is not the case, all of Kanaes would just "shift" one world forward, which, of course can be worse for some of them, though better for some, but in either case for her to just stop running would seem like a best solution.
 * There's not necessarily a Kanae in every world any more than there's necessarily a Kyon in every world (and he's missing in some of them, perhaps entirely nonexistent). For that matter, given infinite worlds, there should be an infinite supply of worlds with no Kanae-- plenty of room to dump all the ones Kanae Prime could be displacing.

The singularity created by Kuyou shall become a person.
As a result of mixing interface-touched data, a force of nature nothing can escape from, a collapsing shadow universe, and possibly Kuyou's body, the singularity will become a person with Nagato and Kuyou as their 'parents'.
 * Additionally, they will be a girl and her name will be Sayuri Yakumo.
 * Sayuri will get involved in the Tenchi Solution. Though not necessarily with Kyon...
 * As a result of their 'parentage' and the items involved in their creation, they will be a Cute Mute.
 * Because Nagato is involved they'll be capable of reading and writing from birth. Talking With Signs ahoy!

Kyon and Tsuruya will end up as Tattooed Crooks.
They're Yakuza, have access to Year Inside, Hour Outside 'technology' and someone who can learn anything, the Tsuruya Yamaguchi-gumi is traditional in style, and the boost to their reputation (especially Kyon's) for the pain tolerance and patience needed to get a traditional tattoo done in such a short amount of time would be huge. Plus Mikuru's the only person in the Tenchi Solution who might not like it, depending on a change in values.
 * Minor amendment: the tattoos would probably be limited to one place. Not as impressive as covering the entire body - but a complete design on, say, the entirety of the back would still be impressive. And why limited? Because any more would probably be enough to worry even Haruhi and irritate Kyon.
 * That and it could be seen as somewhat of a compromise for Mikuru's sake.

Kyon's parents are actually Rika and Keiichi.
Here's the supporting evidence:
 * Rika almost ruined everything. Given how close the Higurashi cast were beforehand, it wouldn't be anything small, even romantic chaos seems a little... weak.
 * Whatever happened must have happened before Rika was 16.
 * Rika married Keiichi, despite almost ruining everything. Mion would be exactly as influential in the village, so there would probably be a reason behind it other than appeasement, since Rika realised what she was being before the divide became too late to repair.
 * Kyon's mother is massively estranged from Keiichi.
 * Kyon's mother has nothing against his being in Hinamizawa in Golden Week but not when his birthday and Watanagashi coincide, despite not celebrating it.
 * Melancholy was published in 2003. If it's assumed that's when it's set, then K:BDH is set in 2004.

Now, to explain: Rika, at 15 and as an orphan, would have been in no position to care for a child. If Kyon's mother's age is placed between hers and Keiichi's, that makes her 16-20 when Kyon was born. Given how she doesn't seem to mind controlling Kyon's romantic future and arranging a marriage at sixteen, it seems entirely possible that her marriage with Yuuto is both arranged and happy, a much better environment for raising a child in than the... mess the Hinamizawa cast were in. The agreement would have been that when he's old enough to understand, he'd be told the truth when his birthday and Watanagashi are the same day, his 17th birthday. Kyon's mother would have agreed at first but - unlike her husband - she noticed the strange arrangement and the Yakuza thing, which, combined with conceiving a child but handing it off and later the only correct marriage, led to her estrangement.

Not wanting Kyon to potentially turn out like his birth parents and having become a lot more attached than she would ever have expected, she would have chosen not to let him find out the truth, coming across as a Jerkass despite her good intentions. There might not even be a legal compulsion to do so.
 * Strikes against this (otherwise terrific) theory:
 * The fic is more-or-less confirmed as taking place in 2011 (from the dates on the FictionalDocuments), and likewise the main Higurashi events are confirmed at June 1983). Rika's Big Damn Mistake appears to have been committed when she was about 12 (Haruhi's comment was "you weren't even as old as Matsuri-chan"), and can't have been later than 1985; Kyon, born in 1994, couldn't be Rika's while-a-teen child even if the pregnancy was later than the original messing-things-up seduction.
 * Possible explanation: Mikuru's reason for heading into the past was to investigate the cause of a time-quake. As well as blocking travel backwards, it might have shifted everything 7 years forwards . The eerie similarities in some films? Different universe, films needn't be created at the same time. And what Rika said could be interpreted to say that she started pursuing Keiichi at 12 but screwed up before 16.
 * Mion had a daughter who was older than Kyon and who eloped when Kyon was in junior high. Hard to imagine her either having a child by someone other than Keiichi or not offering to take care of Keiichi and Rika's child if Rika could not.
 * Possible explanation: Mion wasn't cheating, Keiichi was and being forced not to tell by Rika. Hence the lack of support and possibly another reason to give Kyon to Keiichi's sister.
 * This might explain why Kyon's mother is so very insistent that they recognize and celebrate Kyon's birthday at the beginning of the school year, NOT the day he was actually born- if there's some agreement that he only be told the actual circumstances of his date when his birthday coincides with Watanagashi, she can say, "You/we can't or won't tell Kyon this year, we don't consider this his birthday so it doesn't count as coinciding with Watanagashi." She doesn't want Kyon going to Hinamizawa because they don't care when they count his birthday from, only what his birthday actually is.

Kyon's father is Keiichi, but his mother is someone else in Keiichi's harem.
The same suggestion as above, but with possibly Rena or Satoko... (Mion can't be Kyon's mother by virtue of the fact that it would make the daughter who eloped while Kyon is in junior high Kyon's older sister...)

Yuuto and Kyon's mother's marriage was arranged.
They don't seem to have anything against doing so to their own child and considering how Keiichi turned out, his parents probably didn't want to take a similar chance with their other child.

Kyon's cousin tried to kill him last time his birthday and Watanagashi coincided.
See this post.

The Powers That Be empowered Haruhi with Reality Warper powers as a defensive mechanism to save the universe with tropes.
The crossover with TV Tropes comes in the form of Medium Awareness by the Powers That Be, who empowered Haruhi because her Genre Savviness when backed up with Reality Warper powers ensures a steady supply of clearly identifiable tropes which can be counted, saved, collected and traded for swell prizes. It's a defensive move against the extra-dimensional invaders seeking to unravel reality. By repeatedly using tropes to shore up the structure of the universe with the Theory of Narrative Causality, the Powers That Be ensure that the universe will continue to function as it should in accordance with a blueprint currently being written in the language of tropes, strategically reinforced with lampshades where necessary. The Trope-tan anime that shows up in all worlds is another effort by the Powers That Be to encourage trope-oriented thinking, while Sasaki is doing the work of the invaders by deconstructing tropes whenever she finds them. Haruhi's fear of Sasaki is based on an instinctive recognition of the danger that Sasaki's thinking poses to a universe that is literally built on tropes.
 * The Powers That Be can presumably be found here. Which somehow includes Kyon and Haruhi... Time Travel?
 * The Kyon and Haruhi from the Powers That Be come from a world where Kanae never visited and thus brought the combine and Year Inside, Hour Outside training. So when Yuki couldn't take the stress of Haruhi's junk data anymore she helped Kyon share the burden and thus they transcended.
 * What about Mikuru and Koizumi?
 * They're also part of the overall pantheon appointed by Haruhi, but, along with Yuki, not that high up in the chain due to Kyon's loyalty.

The time-quake mentioned in Melancholy did more than block time travel...
... In the K:BDH timeline. Not only does this tie with the above WMG regarding Kyon's parentage, it explains some (minor) odd discrepancies. Like a computer, new in early 2010 going by the Fictional Document date and minor clues, having a far older looking monitor. Additionally, it covers why the future knew something had happened, due to date changes.

Simply put, the quake separates time planes by forcibly putting years between them. In this case, seven - which puts Tanabata in the 'new' timeline on the 7/7/07... see the connection between Haruhi and sevens? Higurashi would take place in 1990.

Media consistency in new films is weird enough as it is with Kanae's mentioning of frequent differences in new media between worlds, so what difference does creation a few years earlier make?
 * No explanation is necessary for why K:BDH is set in 2011. The original novels were set in 2010/11 (presumably - the 7/7/07 thing was referenced as being considered a lucky number), and K:BDH seems to split off from partway through Book 9. It's supposed to be 2011.
 * Which is from a single line in one of the later books. Book 4 or book 8, I think? It's... odd. That's the one thing to refer to date in the entire series. And the computer monitors still bother me and will until someone comes up with a suitable explanation for having a new computer but not a single non-bulky monitor.

Kyon is going to spend a chapter as a girl.
We're going to need a non plot-relevant chapter sooner or later, after all. And Kyon does keep telling Yuki to use her own judgement with Haruhi's requests... she and Haruhi could decide to play a joke on him.
 * Pray that First Law of Gender Bending doesn't end up being played straight or Yuki's gonna need to whip up a Opposite Sex Clone just to get him back to normal...
 * Then again, we might get a Double Subversion of said First Law of Gender Bending and have Kyon semi-regularly get into situations where he gets temporarily genderflipped involuntarily, needs a physically tangible genderflipped disguise, or just because Haruhi wants to dress "Kyonko" up... or "play" with her.
 * If that happens, wouldn't that make Kyon the K:BDH equivalent of Ranma?

Koizumi will end up with his own Harem
Kyon's got his harem, and Those Two Guys each have one girl. Koizumi, being the second Male lead behind Kyon and ahead of Those Two Guys, he should logically end up with a smaller but respectable harem.

Kyon's mother has a diluted form of Hinamizawa Syndrome
May also count as Fridge Horror, but when you consider that Kyon's mother being Keiichi's sister means that she was likely born and raised in Hinamizawa, it becomes quite possible that she and Kyon quite probably have 2nd and 3rd-Generation Hinamizawa Syndrome. Why does this matter? Considering that Hinamizawa Syndrome induces deep rage in it's subjects, and considering Kyon's mother's primary characteristic throughout the story, as well as Kyon's Jerkass-ness at the beginning of the anime, it wouldn't be much of a stretch to assume that a watered-down Hinamizawa Syndrome could easily cause one to become a Jerkass, as opposed to a psychopath.
 * Really not sure how you can have a diluted form of Hinamizawa Syndrome. Not to mention that the symptoms are psychotic in nature, not psychopathic.
 * There is also probably a cure for Hinamizawa Syndrome now, since Satoshi is clearly not in a coma anymore.
 * Though whether that's a cure for the disease or just the symptoms has never been made clear. Same effect, really.
 * Maybe the cure just stops it from progressing? There's five stages of the syndrome.
 * In stages 1 and 2, there are no noticeable effects, but stress can cause them to move to level 3.
 * At stage 3, they start to become mentally and emotionally unstable.
 * At stage 4, they hallucinate and become paranoid, along with being extremely unstable emotionally. This is about where they start killing other people.
 * At stage 5, they're dangerously psychotic, hear the footsteps of Oyashiro-sama approaching them from behind, begin impulsively scratching themselves, and eventually claw their own throat out and die.
 * In the series, Dr. Irie managed to develop a treatment that could suppress Hinamizawa Syndrome from stage 5 to stage 3 with daily injections. Perhaps the new treatment is also just a suppression? Kyon's mother sometimes acts like a stage 3.
 * After "The Meaning of Everything" (chapter 42), it seems quite likely that at least some aspect of Hinamizawa Syndrome still exists, since Rena has to visibly restrain herself from becoming unstable/acting violently when she learns of Kyon's engagement (the reaction is to Kyon's mother's interference, not the engagement itself).

Evil Kuyou cannot slide.
As a Sidereal, she's too closely attuned to the nature and state of celestial bodies; traveling to a new universe would irrevocably alter her personality or destroy her mind. It hasn't been the same Sky Canopy Domain interface following Kanae; she's met a new one in each universe. Two general possibilities for what's happening:
 * Alternate Kuyous see Kanae (a foreign element in the universe) as an agent of the Noise and try to contain or eliminate her.
 * The Combine are agents of the Noise and at least some alternate Kuyous have Harmonized with them.
 * Appears to be Jossed, since "Resonance Cascade (part 1)" (chapter 47) features alter-Kuyou coming across.

K:BDH!Kyon and Kanae will at some point run into Later!Kyon.
In the penultimate chapter of Later, Later!Kyon runs across a person almost as tall as him who seems strangely familiar and a girl who calls him sempai. They are both interested in his presence. The connection is obvious. As they are running from something, it is either the Combine that is giving a multi-dimensional chase or they are running from Later!Mikuru(small). Alternately, Later!Mikuru(small) is not actually from Later but is instead K:BDH!Mikuru.

Kyon is going to kiss adult!Mikuru into submission, very soon.
He thought once that he's going to get back at her. Another time, he thought that he's going to get back at Haruhi for dragging him by his tie - "right after he gets back at Mikuru". The second one already happened in Prologue/Chapter 42. And so...

Ryouko's action interface is very similar to that of a dating sim.
Blue boxes with white borders and white text? Either that or a JRPG.

Asakura and Kuyou are the author of the title quote for Storm Begins Chapter 4.
During a future event things will be so hectic that Asakura will break her prison and accidentally fuse with Kuyou. After this occurs the resulting entity will be further devoted to Kyon only without the stabbing issues. This is explained by the emphasis on noise and the initials at the ending: "Adaptation" -- LP-K:AR Datastream Segment (-working translation-) K:AR or Kuyou: Asakura Ryouko.
 * Already at least half-Jossed, and will likely be fully Jossed in the future. Durandall posted a correction, saying the letters should have been 'LP-TK:AR', signifiying that it's Kanae, not Kuyou. Additionally, Kuyou has become attached to Kyon in a similar manner to Achakura, but is still her own separate self.
 * I'm pretty sure that TK is Tadamichi Kyousuke (the author of "Practical Heroism and You" and "Roll with the Punches"), not Michikyuu Kanae. Combined with the theory that Tadamichi Kyousuke is Kyon, this makes more sense than it being Kanae.

The above WMG is true, expect that the two retain their individual personality, via Sharing a Body, with Kuyou acting as a Restraining Bolt for Ryoko.
Kuyou may end up using Ryoko's body as her own, and the relationship between possessor and host will end up not only helping the two of them grow via Character Development, but this would also serve as a vital link between the IDSE and the SCD, which would easily become a major bargaining chip that the SOS Brigade would have with the IDSE.

Kyon will get a TARDIS as a Cool Ship, and become The Doctor, with Haruhi and the others as his companions.
Let's review facts, shall we?
 * Kyon is also known by the nickname "John Smith"(Never mind the fact that "Kyon" is also a nickname). This is canon in the Haruhiverse.
 * Kyon can travel through time(with Mikuru's help, of course), and has described time to be "a great ball of wibbly-wobbly, timey-wimey ... stuff."
 * Kyon possesses a tool that he calls a "sonic screwdriver"

Given all of the above, plus the fact that Kanae's "little problem"(The Combine) will likely give the SOS Brigade a Big Damn Problem in the future, it's not too hard to imagine that they would end up making one in order to help and deal with it(and have a fancy HQ while they do so)...

Skynet/Ryouko/Kuyou will join together with TV Tropes.org to create a new data entity.
This will be used against the IDSE to battle it into submission with the awesome memetic nature of tropes.
 * So, Kuyou + Ryoko + Skynet = Trope-tan?

And the IDSE's plan is Immortality for everyone, because they were lonely.
The IDSE rants over the entropic time function, so laments the inevitable Heat Death Of The Universe, and as part of that the mortality of all sentient life. Taking Yuki not as an abnormal element, but as a standard sample it. It's agenda is I Just Want to Have Friends! However it couldn't talk to the MSQCE and all other beings died after only a short time. Asakura wanted to kill Kyon to make Haruhi revive him, thus giving the entity a clue on how to end and reverse Death. They really liked the Endless Eight, because it halted the degradation. After Disappearance in canon, Kyon told Yuki to tell her boss that if anything happened to her, he'd tell Haruhi he was John Smith, and the two of them would move Heaven and Earth to get Yuki back. Chronologically, that's the first thing that happened in the 'fic. Now, Haruhi is generating new data in a controlled manner, exactly as the Entity always wanted. Furthermore,  became fully convinced she'd been set up to be captured by the Brigade mere hours before Haruhi and Yuki helped her , something else the Entity hadn't managed yet but was interested in accomplishing. Now they are slowly building Haruhi's and Yuki's powers in order to eventually being able to just ASK them to turn everybody immortal. Also they have been feeding the NPA info on the Sumioshi Rengo. They aren't working against but for the SOS Brigade. So the IDSE is Eliezer Yudkowsky. Or Rational!Harry's send back through time AI.

Timetravel shenanigans will lead to a trip to ~1000 years previous.

 * Kyon's ancestral sword's history involves a Fujiwara clan. The opposition time-traveler didn't just pick a random alias when he called himself Fujiwara... Something's going to happen, or has happened, and he's either involved, or taking a subtle jab (that will be obvious and/or extra insulting in hindsight) at Kyon with future knowledge.

Haruhi will make Japan legalize polygamy
And all of Big Damn Harem members will take Kyons surname after Big Damn Wedding at the Big Damn Happy Ending. So T.H. and T.K. from the epigraphs will be Tadamichi Haruhi and Tadamichi Kanae.
 * For Bonus Points (unless the WMG already presumes it), she will do it without Reality Warping - perhaps, by Kyon's fame in the ensuing war?

Yuuto will join Tsuruya-gumi
As a driver for Tsuruya-sama. Not sure where it would put him among yakuza rankings, but I'm pretty sure that Kyon, as a saiko-komon would outrank him, technically.

The Sky Canopy Domain are former black holes.
A black hole that goes without absorbing new matter will eventually 'evaporate' into radiation. It seems reasonable that the quantum strings which make up that radiation could be entangled in some fashion, explaining how observation could take place over an area light-years across without communication delay. When Kuyou accidentally created the singularity in Chapter 39, she immediately considered it an entity and it was "unsure" how but capable of Singing. In Chapter 43 Yuki noted that it was "almost as though" Kuyou physically contained an event horizon, because the totality of her strings are still that massive and act on each other constantly.
 * Entanglement does not work that way. You can't use it to send information.

Everything thus far has gone exactly according to the IDSE's plans...
...because they need Haruhi unleashed, and Kyon powered-up, to defeat the Combine.

The IDSE cannot affect alternate realities. Thus, the Combine, based in their own world, is immune from IDSE retribution; they could conceivably just keep invading until the IDSE can no longer stop them. The Combine can normally suborn the Sky Canopy Domain, and with the Combine in control of the local reality, the IDSE's chance for self-evolution, the reason they're interested in Haruhi, is gone. With their position outside time, they detected Kanae sliding into the main reality, and read the imminent threat from her data.

So the IDSE had to take a horrific risk: to gamble that when they gave Kyon advance warning of Yuki's deletion, he would Take a Third Option and merely break Yuki free from their control by giving Haruhi knowledge of her powers, instead of carrying out his stated threat to destroy the IDSE if Yuki were killed (their observation of Kyon and his reluctance to kill made this a much safer bet if he were given time to think -- but not too much time -- instead of a fait accompli). Their understanding of Yuki's psychology provided that, after being freed, she would take steps to make Kyon much more capable of taking care of himself if he were threatened by, say, the Sumiyoshi-rengo, and their understanding of Haruhi's psychology provided that she would create tons of new data. Asakura is being played, and even Emiri may be ignorant of the true purpose of her antagonistic moves.
 * So essentially, it's the IDSE vs. The Combine, in a metaphorical chess game of sorts.

Shinobu is, in fact, a Ninja Maid.
Because Kyon suspects that she is one, and the last time that he made a presumption based on his gut instincts about someone, it was about Kanae being a slider, which turned out to be correct, so...

A Demon would appear at some point.
As it was the only thing explicitly mentioned that alternate reality Kyons knew, aside from time travelers and aliens. All others were just mentioned together as "stranger things". May be even a western-style demon, in the guise of a European
 * Make it Affably Evil Noble Demon in the guise of a European joining the brigade to protect his business from the Combine.
 * Alternately, said demon could be an overlord from the Disgaea series who has discovered that he/she can't go and try to conquer the K:BDH verse if the Combine manage to do so first...

Yukari Yakumo will at least make a cameo at some point in the story.
Why, you may ask? Because it's Yukari, so she can naturally appear anywhere she wants to.

The Terminator shout-outs are not over.
Achakura, after her restrictions are loosened slightly, will obtain/borrow a malmetal weapon to spend a chapter as a mini T-1000.

Elder Mikuru is Really Seven Hundred Years Old.
Through exotic gene therapy or periodic vat-grown or mechanical organ transplants, people from the future are able to remain alive for extended periods of time. Younger Mikuru was sent back at a young age for an extended assignment specifically because she had no obvious augmentations. Elder Mikuru has them, she's much, much older, and she's spent that time gaining experience, trust, prestige, and clout within the organization, possibly even building on her success in dealing with Haruhi. Why else but extreme age would she characterize a crush on a high school student as a Shouta complex?
 * This would also explain why her age is classified.

K:BDH takes place in a Minagoroshi-hen fragment, not a Matsuribayashi-hen fragment.
What Kyon's father said in chapter 50 got me thinking about this:

""Keiichi-kun does good deeds-- He works gratis for villagers on legal matters, and helps advise the town council! Remember that thing you told me about when he was still in high school? When he organized that major protest to help out one of his friends?""

He's obviously talking about Minagoroshi-hen here, or at least the events of it. Assuming this isn't the result of Durandall not looking up what happened in Higurashi, Either the Higurashi cast beat the Big Bad in the Minagoroshi-hen fragment in this fanfic, or Teppei returned to Hinamizawa after everyone beat fate. A number of details show that it's more likely that everyone beat fate in Minagoroshi-hen.

Although everyone dies in Minagoroshi, it wouldn't be that strange if one of the Minagoroshi-hen fragments something different happened. After all, some similar fragments have had variations and different events in them before, like in Tsumihoroboshi-hen. In all of the worlds similar to Tsumihoroboshi-hen, Rena went insane from Hinamizawa Syndrome and blew up the school. However, in the Tsumihoroboshi-hen that we are shown, Keiichi manages to create a miracle and stop Rena from blowing up the school. That was the first time Rika ever saw anyone beat fate, albeit temporarily. It's then entirely possible that in this fanfic something different happened in the Minagoroshi-hen fragment.

Another thing that makes me think that this is Minagoroshi is that in Kyon: Big Damn Hero, Hanyuu cannot become corporeal on her own. It was only in Matsuribayashi that she could be seen and heard by everyone else. Also, when Nagato offered to make Hanyuu corporeal, Rika worried if Hanyuu would be harmed in the process; which implies that Hanyuu never had a physical form when everyone was fighting fate.
 * Maybe a Heroic Bystander in a greatcoat from another time showed up just after the reveal of the Big Bad and defeated the Yamainu before any of them could kill anyone.

The reason Kyon lost his smile wasn't just because Sasaki crushed his feelings by deconstructing love...
...since she deconstructs things by not believing in them (or vice versa), she actually eliminated the concept of love from reality in her vicinity. She didn't just step on his feelings for her, she wished the fundamental aspect of reality that allowed them to exist into the cornfield. The only reason that stopped is that she found herself experiencing that very emotion, and therefore couldn't deny its existence anymore.
 * Scarily possible as the cause, although given Nonoko's track record and the number of times she refers to Haruhi 'fixing' Kyon it seems likely that it was actually Haruhi's powers that undid the damage.

The semi-abrupt end of Negima was caused by Haruhi and Kyon's discussion of manga length in chapter 27.
Akamatsu Ken will continue the story in a set of sequel titles which will conform to Haruhi's 'volume limit.'

Haruhi is Alicorn
She's the author of Luminosity and Elcenia, if you're wondering.

Haruhi modified herself to be polyamorous. Where have I seen that before?

Haruhi is going to be reading Negima at some point.
It's been made pretty clear Haruhi is a troper, and it seems unlikely that everything on here doesn't exist in that world, so she's bound to be reading something like that. It DOES have magic and Haruhi's bound to appreciate the fanservice.
 * And then there's Negima taking Unwanted Harem Up to Eleven in its own Love Dodecahedron aspect. She could use a few pointers.
 * Proven right in Initial Conflict Chapter 4. Haruhi stated outright that she reads Negima. She's not too happy that it's ongoing though.
 * Though, reading between the lines, her big gripe is actually that she likes it so much she keeps having to wait for the next installment.

Haruhi is going to take advantage of Kyon's PDA's disguise function.
Haruhi did say that it wasn't just the girls that would be dressing up. With Kyon possessing the ability to appear dressed in any manner scanned...
 * It happens in Thwarted Lull Arc, Chapter 5. Haruhi discovers that Kyon's PDA can scan pictures from the Internet and renders them as holographic disguises. The first thing she does is make Kyon wear a Victorian suit, followed by various outfits from the same era.

Kyon is going to get the beam saber at the beach.
His sister brought the sword's hilt, everyone needed for Haruhi's powers to be used is present, and now would be a really good time to have such a weapon.
 * Confirmed in Thwarted Lull Arc, Chapter 3. They defeat the giant alien attacking, and Yuki morphs it into a blade for the hilt. He hasn't trained with it yet, but he has it now. Also, he starts doing the "voiceover" thing that excited Haruhi so much in the prologue, except that he doesn't have the poetic names for the weapons yet.

Kyon is going to name his weapons Altair and Vega.
These are the stars linked to the legend of Tanabata (Vega and Altair represent Orihime and Hikoboshi respectively). This was mentioned in detail at the start of the story Bamboo Leaf Rhapsody of the light novels. As bonus, both names are guns' names in the PS2's game Final Fantasy XII. The game was released during 2006 (at the end of the chapter thirty one, the date in-story appears to be May 21, 2011) and Kyon owns the game system according to the story, so it's not unthinkable for him to know about this.
 * Confirmed in Open Battle Arc, Chapter 5.

Sakanaka isn't attracted to a boy.
Instead, one of the ENOZ members (even though they're no longer definitely in education) or a member of the SOS Brigade.
 * Jossed by Calm Before the Storm Chapter 5. Sakanaka is attracted to Kunikida, but she suspects that he's attracted to Sasaki.

Kanae keeps drawing Yaoi.
She IS a Yaoi Fangirl.
 * Alternatively, what she draws is not Yaoi, but is instead her secret plans or something along those lines. She just acts like she is drawing yaoi to throw everybody off.
 * I think she simply draws Kyon. Over and over and over again. She hides it because understands how creepy that is.
 * Yaoi confirmed. It's not like it is all that she draws, but it's there. Koizumi and Kyon didn't enjoy that.

Nonoko will likely pull off a Big Damn Heroes moment, which will once and for all prove to Kyon that she can be trusted with secrets.
Because it would be awesome and it would prove that being awesome runs in the Tadamichi family.
 * As a Magical Girl!
 * I Knew It!