There is runtime unification but the user interfaces are still well separated based on the target device and screen size. I suspect the end game is one app package that runs on phone, tablet and desktop with specialist UI for each platform.

So far they are doing extremely well. I can hop between all devices mostly transparently. And the desktop has not been dumbed down; all interfaces have been improved on their target devices. I have got to the point my iPad is my go to machine now.