The hand motions of such a game would probably work similar to the playstation's eyetoy gimmick, and would be an extra optional function, like in some of the more recent ddr games. The difficulty of the step patterns is still questionable, however, given the easy difficulty of mario ddr, nintendo's last console contribution to the ddr scene. On the other hand, the main complaint from reviews of mario ddr was the easy difficulty, so maybe nintendo will take it up a notch as response.