I briefly touched on this in the post, and did kind of hand-wave it away, but this Reddit comment sums up my research: http://www.reddit.com/r/Games/comments/18irx0/the_minecraft_...

Now, I'm really curious about the next-gen Xbox, which will almost undoubtedly be built on a version of Windows 8. Hopefully this means the same tools for developing Xbox, Windows Phone, Surface, and desktop apps (HTML-based, if I recall)