Since Windows has started this iteration of their move to ARM, I wondered if Microsoft would be the first to do this properly, by building an adaptable/mobile Desktop/UX to Windows 12 (or 13), pumping up the Microsoft Store, and then relaunching the Windows (Surface, I guess) Phone with full fat Windows on it.
In a way it's the same strategy that Nintendo used to re-gain a strong position in gaming (including the lucrative Home Console market where they'd fallen to a distant last place) - drafting their dominance in Handheld into Home Console by merging the two.
If they really try to make a convergent Windows phone, I think they could make it if they manage to integrate Android apps into the Windows mobile UI. However, we are talking about Microsoft, so I doubt they'd actually manage to do it.