PC with a Linux chip that boots instantly into Chrome, and have Google and Gmail as home pages... I can see it.
I don't think people will actually prefer ad supported OS.AD supported sites are one thing but no way in hell people will use Adsupported OS with shitload of ads.Microsoft will dominate OS market for ever.
I think Google is continuing its research on what internet people needs. The OS thing yes may be in future. They are creating their domain all around the world.
A web browser is ALMOST a OS for the web you need it in order to BE on the internet thus I don't think they need to invest on creating an OS !! quite often I wonder about this !!! Its amazing how much they know about us !!