8 out of the top 10 manufacturers are Chinese. Google has to be careful here, otherwise Android will end up as a Chinese consortium and their own version will just be available on Pixels.
That's the huge, huge carrot that Google carries in front of everyone thinking to fork Android.
Google does have a card to play here, I don't disagree but they shouldn't overstate their hand either. The Google bits of Android are good enough to keep open-source ROMs and small manufacturers away but they aren't a silver bullet and won't save them if China stops playing the game.
I highly doubt that. People have far too much money already invested in Play Store purchases, that's a lot to give up for a marginally cheaper phone.
Also, I don't necessarily think the phones will be marginally cheaper, just that the market will adapt.