I don't get it. Mojang already made "all the money" from selling minecraft and are largely maintaining it now. I haven't heard if they even have any new games on the way? The space one was cancelled. What exactly is MS possibly getting that could be worth $2B?
Even if we ignore the VR/AR stuff, Minecraft with Kinect would be loads of fun. The Kinect's killer app may not be been dancing games. It could be world-building games. Imagine lifting your hand to move a brick and flicking your wrist to toss it.
...and thats on top of revenue MS would make on more traditional Minecraft monetizations. Look at how Disney is re-invigorating the Star Wars IP. Suddenly new movies and games are coming out. We're finally getting a third Battlefront and upcoming movies that seem under the aegis of more... competent creators than the recent prequels (Sorry George!). People are more excited than ever about an IP, that frankly, has been treading water for the last 20 years. MS could do something like that to Minecraft, which always seemed more than a bit under-commercialized.