I dont think 360 owners will have that much interest.
There has been very little use for the sixxaxis on the PS3 since the early games, and nobody is really complaining.
When it comes down to it, when it comes to console gaming, extra gimmicks are nice, but at the end of the day, its never really missed as long as the games are good.
The Wii though has had its whole foundation built around it, which appeals to completely different market!