Not sure if anyone in the audience would care enough to say that. The crowd would more likely be casual gamers and I'm not sure if a good amount of them even know about the Wii U existing (which can be crazy to believe) or care that it's releasing next year instead of 2015 (look at the droves of people running to play the demo at E3). And I'm not sure if they would behave like that. They'll probably boo Nintendo for taking out the fan games (which why would the creators open themselves up like that using the actual name/similar assets of the two games removed from the fan game category). Other than that, I don't expect much but cheers once the Zelda footage comes up.

Meh, I already know the game is awesome and that I'm going to buy it, so I don't want to see anymore footage as that'll only ruin the exploration and puzzle solving.

You'll get that on Jan 12!

They can still show the switch version and give a release date for Zelda without revealing more about the switch itself.

Why do you think most of the audience will be casual gamers? I don't think they'll be interested in a videogames award prize... (Or maybe we understand something different for "casual gamer")

They can but they want, they will keep infos like those (all release dates) for Switch event in January, also Nintendo usually gave release date only around 3 months before actual release of game.