Why would Nokia want to be another Android pusher with no competitive advantage? Value-adds on Android are all shit (crappy launchers and bundled shitware) and the platform is fragmented to fuck. Firefox OS isn't even off the ground and Ubuntu is dead as well.
Nokia hit the spot with windows phone. People will realise that in time.
The platform is worth it just for Nokia Here+ for a lot of people (myself included) and the fact that the hardware is decent.