On the one hand, the cartoony graphics and simple, casual-friendly gameplay of Katamari seems like a perfect fit for Wii. On the other hand, the dual analog stick controls are so ingrained in the series, it's hard to imagine how it would be the same game without them. (They tried it with just one stick on the PSP, and every review I've read of that game trashed the control scheme.)
I do expect there to be a Katamari game for Wii eventually, but I don't know how they will manage the controls and still have it "feel" like Katamari, short of requiring the Classic Controller. Maybe the game could be sold as a bundle with a Classic Controller, like how Wii Play is bundled with a remote. That doesn't seem too likely though.