I think motion controls are here to stay. They add another dimension in gaming. Just like I think 3D will do some day, and eventually Smell-O-Vision till we finally end up at a Virtual Reality like the Holo-Deck on Star Trek.
But then I think many people would enter the 'World of Warcraft Holodeck' and never want to come out again. You fight all you want, cast spells, and never really get hurt.
I think Kinect shows the most promise, but forced feedback in a controller (i.e. it pulls against you) would be another innovation.