Windows mobile phone forays are dead, done, finito, kaputt and out of steam.
Windows Phone 7 has been out for almost 4 years and still barely holds 3% market share. Thats pretty awful by any measure, especially since the platform before it had much larger market share. They lost customers with current platform without gaining any new ones.
Windows Mobile was out 7 years and failed, and before that Microsoft failed with Pocket PC.
I am amazed they still happily beat the dead horse instead of putting effort into supporting the winning platforms. Android will be succeeded by something in the long run and until then i fail to see the business perspective of dragging a dead horse round the racetrack with a lawn mower trying to catch up with a Jumbojet. Why not just book a seat in the Jumbojet instead?
Personally im sure Nadella would like nothing better than to put a fork in Windows Phone, but entrenched forces inside Microsoft makes this very hard. It has to fail on its own dying a long agonizing death instead.