Honestly, I do place my bet that this is where Prime 4 gets properly revealed. It's about time, and would make sense if they pair that with an announcement of the trilogy getting ported with HD graphics (similar to Bayonetta 1+2 and Bayo 3 both being a paired announcement.
If not, I suspect something will be talked about of Zelda. Whether DLC for the 2 year anniversary, or something else; I wouldn't be shocked if that gets a brief moment (considering that did get GOTY).