By the time he was CEO it was already dead. He was right to kill it.
I have my doubts that a three-horse phone race would have been stable in the first place, as one of those three (Android, iPhone was too established) would have likely fallen out of favor. And then, you all would be complaining about monopolistic practices Microsoft would inevitably be doing.
Google is not a good company, but they have treated Android much better than they could be.
Had Microsoft succeeded, things could have ended up the same as the pc market, with windows being used by big brands and Android being used by companies like 2011 Xiami, making highly customized experiences and that sort.
They say Microsoft lost Samsung to Android by being one month too late. Had they finished that first windows phone one month earlier, everything would probably be different today.