I am not sure, first what Gahars said but I should also mention there is something to be said for MS ensuring that every user has a kinect device.
Now I am certainly not sold on the virtues of the Kinect but there have been a few examples in games history of why you do not sell optional extras (required for some games) at a price point above the N64 expansion pack* or maybe something like the megadrive 6 button controller.
*that the N64 expansion pack and megadrive 6 button controller also represented a real and worthwhile upgrade to games did not hurt matters either, motion controls have added decidedly less to gaming beyond making sure the Wii had a built in audience for badly handling rail shooters.
Right now it seems all the current consoles, give or take mainline android, are selling on some "future potential", though Nintendo's promise of future potential is wearing very thin indeed on all fronts, and future potential is the first step on the path to failed to meet promise/potential and I really hate it when that happens.