Will MS go down the Apple road?
..of only allowing reinstallation of the OS from the cloud? That way they can make a 'clean' <ahem> image available to all who have an activated legit OS installed. Big draw back: they pay for the hosting infrastructure and if your line in the boondocks is too slow you'll never get the image (Oh yeah, trying reinstalling OS X over the web on less than 2Mbps and see you connection disappear into a black hole somewhere in the US)
Why stop there? When your data is on One Drive and your use Office online (or whatever it is called this week) all you need is a browser. Oh yes, that's the Surface / Windease phone isn't it?