Me thinks they'll have a traditional controller this time around. They're probably just holding back to showcase the 6.2" touchscreen. With PS3's market share shrinking against the 360, now's the chance for Ninty to take a piece of their pie, especially considering Japan loves the big N. Also, sticking to the non-traditional gamer market for another round is questionable since much of that demographic won't jump for an upgrade.
Mark my words, though. There will be a traditional controller in the future. :)