Exactly one year ago at the game awards we got the last extensive look at Zelda U (see here). Except for a small snippet at the last Direct, we didn't see anything else. So, I'm pretty sure that we're going to see Zelda U again tonight. What else would they show? Certainly not the NX and they already showed a lot of Starfox Zero (Effort) this year... So, it's time for Zelda U again.
Also, the demonstration last year was an important turn of events. There have been many concerns that the world looks to empty, which probably was one of the main reasons for Nintendo to delay the game for an entire year. And now it's time to show what they have accomplished in this additional year. They need to show the difference, to show what you can explore and find.
I would also like to see a dungeon. So, maybe do something similar to last year. Start in the overworld, explore a bit, show that the world has more to offer now and then go into a dungeon to show what has changed here.
Update: Or they could just show nothing at all... too bad.