Animal Crossing seems possible, it's one of the big titles that makes it to every system that the Wii U doesn't have yet, and they already have that Animal Crossing Plaza thing on the Wii U, so they're probably thinking about it. Might not do it this year though, no need to kill the momentum for the 3DS game. Metroid seems really likely, since they hint at it now and then, like Reggie's Samus pin at the VGX awards. I think it's quite possible it might be an early announcement of the new Miyamoto IP though. They'll want to announce it and build hype away from E3 so their new IP doesn't have any competition for attention, and then when they've got people looking at it and excited, then there will be another big reveal of it at E3 as well.