For Wii U, I expect we will get trailers to hype up the coming exclusives as well as gameplay streams. Specifically:
Xenoblade Chronicles X
Zelda
Star Fox
Devil's Third
Mario Maker if it isn't already out
Yoshi's Wooly World
Potentially one other game not announced yet.
There will probably be a number of things announced or elaborated on. Specifically:
Rodea the Sky Soldier
Project Treasure
A Prime style Metroid
Animal Crossing
A new 2015 game, probably smaller
Wild card: 3D Mario, F-Zero, something like that.
We'll also probably see indies get talked up a bit. Fast Racing Neo hopefully, Freedom Planet, and a few other highlights.
I also wouldn't be surprised if there was a Splatoon tournament for hype reasons since it will be recently released.
SMT x FE is another possibility
