Its just Microsoft realizing since they were late to the smartphone explosion and late to tablet hardware they may as well try to integrate into everyone else's stuff. Which is the logical way of doing things considering they still have some pull. Too many people still use a PC and they never reflected on that.
And there is where Microsoft is still playing catch up. Its nothing Google hasn't done. You'll still need Apple products for the Apple ecosystem. You don't need Android for the Google one. Now MS is playing the card they should have been playing all along.
As for a universal platform, it is a great idea. Both Apple and Google are/were moving towards it. For once in a long while MS can carve a path and show them how its done. Just hope the current CEO can keep to understanding that vendor lock in doesn't help them when they're trailing. And it won't end well then they're ahead.