Microsoft are so well placed to create and distribute what is bound to become a popular from factor. This would work on so many levels. The light-weight basic consumer that doesn't need a gaming/ or other high power rig at home. Developing countries where people can't afford a laptop and high-end phone could now get a phone plus a screen/keyboard at home. And the biggest sell is at the enterprise level. Companies could issue phones only and have a heap of docking stations. It wouldn't suit everyone but many would.
Time to re-visit Ubuntu Touch and see how they are getting along I guess.