Caution: I may have had some sugar before writing this, and these predictions are for entertainment only and should not be taken seriously.
DS original: Layton and Kirby are fall, Pokemon Gray is getting fast-tracked for a March 2012 release and that will be the DS's last hurrah.
Wii: The theme is epic adventure after Kirby's reveal. Zelda, Xenoblade, Last Story and Pandora's Tower all come out by next E3 (the first 2 by the end of the year, Last Story in January and Pandora's Tower in March), and a mention of DQX which is still coming to the Wii. WiiPlay Motion gets a 1 minute video and that's it. In my dreams, the Dream Team reunited one more time to bring us Chrono Resurrection for a early 2012 release (and a director's cut of Chrono Cross comes out on Wii, killing every useless character in the process. You'll have 10 to finish the game with.) Also, Mother's Day gets moved to the Fourth of July this year with a stunning WiiWare release that someone in the Treehouse has been working on after hours for about the last 2 years.
3DS: The Christmas headliners are Mario 3DS/Mario Kart 3DS. e-shop gets a vague mention and the Oracle Zeldas, complete with automatic save detection. No F-Zero or Smash, those get saved for...
Super Wii (aka Cafe): Cafe is announced as the name... of Nintendo's new online service, which will launch day and date with the new Super Wii. There's too much brand equity in the Wii name to toss it away, which is why one of the tech demos is "Wii Sports Cruise" (working title). There is a screen on the controller, it's not 6 inches but is extremely high-res, drawing iPhone comparisons. No details on storage or even disc format, but some PR flack will leak something about 30GB disc capacity sending the Internet into a tizzy of HD-DVD rumors. The wall of logos will include Dead Space, CODBlops 2, Final Fantasy - but it's explicitly NOT Crystal Chronicles - and the Guillermo Del Toro/THQ joint production. Yves Guillemot of UbiSoft will run out on stage to proclaim how excited they are to bring their quality of Wii/DS production to Cafe - at which point he gets pistol-whipped by Reggie, who brings out Gabe Newell to announce that the back end of the online service is Steam. The first product of this partnership? Half Life 3, day and date on PC/Cafe.