I would like to predict that the Wii U will show up and help Nintendo win E3 this year. When I say show up I mean coming in and ruling the show. Lots of games, finished product, with all the bells and whistles.
The Wii, Ds, and 3DS will all bring something to the table as well. The Wii and DS just to show that Nintendo is not going to abandon its owners, which will bode well for them in the future. The 3DS will showcase the 3DSi.