They would have to do some sort of virtualization since there's literally no restrictions on what APIs you can access. There's so much cruft and invalid paradigms in the old APIs it makes sense to roll new ones.

I think the approach they're taking to refactoring the Control Panel into the Settings App is smart. They're dog-fooding the Frameworks they're expecting others to use, slowly migrating functionality that's relevant to a modern Windows platform, and keeping existing functionality around until they've replicated it.

I also like that the apps are responsive. I use the snap feature a lot and it's nice that the Apps will adapt to the dimensions I relegate them to.