The Legend of Korra/WMG

WMG for The Legend of Korra

The Cabbage Merchant in the new series will also be the foaming mouth guy.
The Cabbage Merchant had a daughter who ended up marring the foaming mouth guy after the end of the series. When The Cabbage Merchant dies the foaming mouth guy takes up his business to make his wife happy. He ends up having a son who inherits the foaming mouth guy's... foaming mouth. He also takes up the family business. Now whenever Korra and her gang destroy the cabbage cart, the new Cabbage Merchant has a seizure.

"Cabbages guy" will have a reincarnation
Preferably female and younger. She will appear in one episode, or maybe a few, as a ditzy successor to a cabbage shop who is having troubles adapting and living up to her families expectations.
 * Or she'll actually be good at her job and be bummed out because having your cabbages ruined several times had become a family tradition.
 * Or maybe she'll even be cabbage bender. Because nothing screams Rule of Funny like a background character her cabbages being seemingly ruined and then flying back into her cart like nothing happened.
 * There's a funny entry in CAPSLOCK_ATLA about a "Cabbage Madame", who runs a garden-themed brothel. That's not going to happen on a Nickelodeon show, but I think it'd be hilarious.
 * ...I am too scared to even think about how a cabbage-themed brothel would work.

The cabbage merchant will be the one who started the whole anti bending group.
The cabbage merchant after suffering again and again from the actions of even the "good benders" gets disgusted and realizes that the only way cabbage merchants' cabbages will be safe is by ending bending.
 * but it wasn't always benders that destroyed them, don't forget the Customs Officer at Ba Sing Se.
 * The Equalists will also be against bureaucrats. It's not as prominent as the anti-bending, but it's there.

The Cabbage Vender's ancestor will come back as a good guy.
Except he will retain his Buttmonkey status and basically be treated as badly as Bakura was in Yu-Gi-Oh abridged.

Korra herself is the Cabbage Guy's descendant.
Eternally conflicted between her Avatar duties and her cabbage-selling family. Angst will ensue upon destruction of cabbages.

The cabbage merchant's luck turned around after the war ended, and he is now the richest old man in Republic City.
He will have made his fortune exporting cabbages to the Fire Nation and North Pole, where they are used in exotic foreign dishes. After a lifetime of successful cabbage selling, he retired in Republic City and now considers joining the White Lotus Society.
 * Well, Nick.com DID reveal that a corporation called Cabbage Corp made their own Cabbage Cars. Founded by the Cabbage Merchant maybe?

The Cabbage Merchant's legacy will take the form of a Starbucks-like cabbage franchise.
It was started by the Cabbage Merchant's illustrious descendants, eager to make a profit from their ancestor's secret formula for the perfect cabbage. True to form, practically Once Per Episode, Korra will somehow damage one of the many shops in the franchise.
 * Jossed. They're a tech/industrial company like Sato's future industries.

Amon will be the descendant of Cabbage Guy.
He seeks revenge upon all benders for the (multiple) loss(es) of his ancestor's cabbage cart(s), which ultimately led to his financial ruin and his family's Start of Darkness.
 * Amon claims to be the child a farmer. Where do cabbages come from again?

Tenzin and the Cabbage Merchant's descendent will have a Vitriolic Best Buds-type of relationship
It will involve Aang trying to make peace with the Cabbage Merchant after the trouble they've caused him during the war. However, Tenzin will steadily grow to find the child of the CM increasingly annoying. Years later, in Republic City, the Cabbage Merchant's child will become a successful lemon merchant while Tenzin has trouble living up to his father's legacy (that or was forced into hiding because of the anti-bender faction). The lemon merchant then does whatever he/she can to cheer up their childhood pal... by giving Tenzin lemons. Korra will happen upon the poor unfortunate moment where Tenzin will snap because "I don't want your damn lemons, what the hell am I supposed to do with these?". He will then proceed to force Korra into making the lemons explode with firebending--to the point where it becomes a technique. If the friendship is Type A, the lemon merchant will remain oblivious to the malice and just think Tenzin is confused. If the friendship is Type B, however, the lemon merchant is secretly avenging his father and is gleeful at the absolute irritation it causes for Tenzin.
 * Jossed. Tenzin and Lin arrest the poor guy.

Bumi when introduced will take on the role of the Cabbage merchant
Being the only decedent of an airbender, let alone two powerful benders, who isnt a bender you can tell the universe loves to screw with him
 * Jossed. Cabbage Guy's descendant did.

Cabbage Corp will become a Mega Corp now that
And in revenge against the Equalists for setting him him/the Krew actually saving his corp/a cabbage cart that's an heirloom, he gives them a brand new car... that's shapped like cabbage or is actually beautiful, but a lemon.

This world's Cabbage is our world's Babbage.
One of the members of the Cabbage family, or at the very least an employee of Cabbage Corp, will invent the first proto-computer.

No one is Batman.. but Bolin is the Fearless Ferret

 * Naturally, Pabu is Wonder Weasel.

Korra is a Ninja
A guy can dream can't he.
 * Refer to the "Korra will be as Batman" WMG
 * Alas, Korra is almost the exact opposite of any Ninja tropes.

Korra will become something even more awesome than Batman
She will become BAT WARTHOG MAN!. It's the best two-animal combo (and thus, in the Avatarverse, it must exist).

Everyone is Batman

 * And by everyone, we mean EVERYONE.
 * In all seriousness, the Batman parallels are flying hard and fast, and we are only three episodes in. At last count, we have three Batman parallels: Korra learns that her vigilante justice may be what the city deserves, but it sure as hell not what it needs, Mako witnessed his parents being mugged and murdered by a firebender at the tender age of eight, and Amon invokes the archetype of the mysterious masked man here to save the populace from it's superstitious and cowardly criminal empire of benders.
 * Aaand, Amon has a deformed face and is fostering dissent and anarchy, a la the Joker..."Hello, beautiful. Y'wanna know how I got my scars?"

Korra takes place in the same universe as Batman Beyond
Here's some of the parallels between this series and Batman Beyond. Namely, the large time gap between the two Sequel Series, the new hero gets an older mentor.

Mako will lose his firebending.
He will actually become Batman.

At least one of the writers is a Batman fan
And they're throwing in references left and right. They're also a really big Batman Beyond fan. Evidence:
 * Mako's backstory is Batman's, minus the wealth
 * In Episode 6, the Wolf-Bats pose like Terry from the Batman Beyond opening
 * Lin Beifong is very much like Barbara Gordon, as the second generation police chief of a crime-ridden city who doesn't look too kindly on the new hero
 * And now in The Aftermath,
 * Sounds more like The Punisher to me
 * Thanks to "When Extremes Meet" we can now all say "QUICK! To the Korramobile!"
 * The matter of the new Chief quite clearly - willingly or otherwise - working for Tarrlok has the feel of Batman to it; a police force dominated by corrupt officials.
 * Episode 9 is titled "Out of the Past," a name it shares with one of the most popular episodes of Batman Beyond.