All rumors. But source is Paul Thurrott.It would be based on the same platform that powers Windows 8 and Windows Phone 8.
It is likely to be priced at USD 499. A cheaper version would be available for USD 299 with a mandatory two year Xbox Live subscription.
Microsoft is delaying the rumored set top box based on Xbox platform.
Next Xbox would come loaded with a Blu-Ray drive!
And it would require constant internet connectivity.