I think the Kinect 2.0 and the Windows TV/full Windows 8 stuff will help drive XBox sales, not hurt them.
These leaked specs are still a fairly large upgrade on the existing 360, 1.2 TFLOP GPU is more than 5x the 360 and add in that its a more modern architecture and likely is tweaked to be more efficient with DX11 effects, you're probably talking about something that's more like 7-8x jump with a massive amount of RAM.
It will still have all the Halos, Call of Dutys, Gears of Wars, Forzas, Madden NFLs, that core players want, but the added functionality will allow it to appeal to the iPhone/iPad audience too who want more than just a big fat box that plays video games.
The Vita is the handheld that "core players" would've designed, and look at how badly that's flopping. MS is right to hedge their bets more on getting a wider variety of consumer. MS can do this better than Nintendo can because they have more "street cred" with the hardcore crowd, so they can maintain that audience.
I'm sure the 720 will have new IP too, MS has backed off from pushing too many 1st/2nd party IP on the 360 later on because they want third parties to have the lionshare of the software pie.
