In effect Android is proprietary already ...
... because GMS is. Most importantly Google's stranglehold is cemented by GooglePlay, which at this points enjoys an unsurmountable advantage due to network effect*. (Not that coming up with the other components (browser, maps, ...) would be trivial, never mind something phone manufacturers on razor thin margins were likely to pull off or even try.)
* i.e. the value of a product or service to an user increases as the number of users increase, which in this case happens because of the feedback loop of: more GooglePlay users -> more developers using GooglePlay (exclusively) -> more GooglePlay users -> ...
Biting the hand that feeds IT
