Makes you wonder if they'd have been better off making a new OS. Maybe make it run on the Xbox One and have a "computer" bundle where it comes with keyboard, mouse etc.
This new OS would do everything they seem to want to do - just run store apps, be more secure, collect usage data etc. and provide a device that could be sold to non-tech savvy users.
They could then have left Windows as it was - legacy software and everything but allow it to run the store apps if you want - just another universal apps target.
I've been recommending Chromebooks (and even tablets) as PCs for people for some time - a lot of people don't need all the legacy stuff (and *will* try to install malware no matter what you tell them) - for those people an "XboxOS" which looked like Windows but was secure would be ideal. And Windows for those that actually need it.