To have this loltastic sentence at the top of hn makes me wonder if MS or some PR has a bunch of shill accounts they roll out for occasions like this. Seriously? As the other reply said, they were already together. And losing. Badly. And hated, broadly.
And the reason the windows phone sucks so badly is that MS tied the PC and phone UIs together into a "push-me pull-you" (Windows 8 everywhere) that can't succeed at either task. And so to escape MS will have to back out of their deal entirely, go back to designing phones and PC OSes separately, and given MS' ingrown bureaucratic insanity there that seems less than likely.
Grafting a few more limbs onto a failing Frankenstein will ... create a bigger failing Frankenstein.