It doesnt have to be their main controller either.
Making a game like Wii-sports or Wii play, I would imagine would be pretty easy on an Xbox360. They could release games on the XBLA that could use motion sensing. With 10 games with low graphics this could be done by next fall. Release it as a motion sensing bundle and there you have it.
They could make bundles that include the controller, and those that have the classic controller.







