On the other hand, they've got another two systems they can pretty much ignore.
30 Wii U
But that's only barely enough time to show everything they need to show for Wii U, since I would expect that they're going to announce a shitton of games and have a few on-stage demos. Wii U should have 40 minutes ideally.
Of course, Nintendo could fix this issue by killing that damn NDA. >_>; Maybe we'll get lucky and it ends up taking an extra 10-15 minutes.