Look, Windows was/is a strong monopoly, and yet it ceded most of the hardware decisions to manufacturers, who also add all sorts of bloatware to the OS and mess with the UI, provide their own more "friendly" skins, etc.
Plus ca change.
We definitely live in interesting times. My professional opinion is that there's room for one or more players in the smartphone OS market. Windows 8 phone could be one, if it catches on. But seems the real demand is for a mobile operating system that has consistent, smooth user experience and a ton of content like iOS, and customizability and open-endedness like Android. Seems unlikely at this point, but with technology, you never know.