Yeah, uh, have fun with that. Microsoft tried that with the Windows Phone but it sucked because of the lack of apps. From what I remember, they weren't terrible phones per se, they just had no third-party support. Granted, it sounds like they're being proactive in trying to get app developers on their OS, but for me personally, it's usually the small, niche things that can make or break a device for me.
I actually kinda wish Microsoft would bring back the Windows phone now that phones have gotten significantly more powerful and Microsoft has their universal windows platform thingy alongside their cisc compatibility layer (I could be wrong, but I'm almost certain I remember reading that ARM windows has a compatibility layer for x86_64 programs). I probably wouldn't buy one, but it'd be cool to see what kinda competition would come from having a phone platform that has compatibility with most windows programs.