Time isn’t something that is given though is it.
Look at the wii motion plus, no games use it because no one is bother to develop for a small proportion of the market.
I have some seriously interesting ideas of how you could use Kinect, but they are several years off and require extra tech.
Kinect games will be a small proportion of market as many of the current games genres cannot be played with it, however, if the finesse is there an interesting RTS could be done!
If the plan is to transform the xbox into a media centre, why not just concentrate on that and veer away from "Eye Toy" games that seems to be being developed now?