Arcade Fire/WMG

The unidentified "runner" in "The Wilderness Downtown" is Todd in The Shadows.
The Faceless? Check. Gray hoodie? Check. Piano music? Check.
 * Todd, in one of his videos, says he was happy that Arcade Fire (among several other indie bands) made it big, so apparently he's something of a fan...

The fourth album will have three title tracks.
Funeral had none, Neon Bible had one, and The Suburbs had two. Why not continue the progression?

The Grammy Performance was a giant "Fuck you" to the Grammys.
Think about it: why would they choose one of the less impressive songs on The Suburbs, have blinding streetlights, and threaten professional BMX bikers safety? It was all a massive trolling.

"Sprawl II (Mountains Beyond Mountains)" will be the last single off of The Suburbs.
Penultimate track off of the album? Check. Extreme popularity among fans? Check. Hell, it's even being played as the last song at a lot of the Suburbs tour shows now, a position usually going to "Rebellion (Lies)," "Wake Up," or "Intervention."
 * Confirmed! It even has an interactive music video as well.

The next album will focus on the subject of families
They've focused on childhood, growing up, young adulthood, and there's that haunting line "I want a daughter while I'm still young".