Interesting that they are aiming to such high-spec systems. I guess they need the performance to run existing games at adequate speed. But trying to go to retail with a $1000 box (my guesstimate for i5-4570/gtx760 setup) will not be easy.
The situation is actually quite similar to the Android world. Google makes the platform and others make the phones, Valve also provides a platform and lets others make the steam machines.
http://www.tomshardware.com/news/amd-mantle-api-xbox-one-pla...
And I think that i3/660 is fairly well balanced entry level futureproof for 2 years 1080p machine.
A niche, but a decently-sized one.
And depending on the living room - it may well be worthed. Having multi-TV screen gaming setup with audiophile sound can be very lucrative niche market.
Be I could definitely see the fat headless home pc streaming to the devices needing it in the next few years - we could call it home mainframe.