You say "is" as though they haven't changed CEO's, undergone a complete organization rehaul, and oriented toward cloud services in the ensuing six years.
(minor edit for clarification)
Windows won't go away but will just become less relevant. I doubt Microsoft even cares if Apple takes 80% marketshare in desktop/laptop PCs... as long as people keep buying Office licenses and using services running on Azure they'll make a ton of money and everyone wins.
The mobile race is over. Apple and Google won, we are way too far along in the hockey stick graph to leave any oxygen for further competitors. The only question left for anyone else is how much money they want to lose before they give up.