Plus, it's not like Android will suddenly become less viable if it were to drop from ~85% to 65% market share.
Disclaimer: I work at google, but in an unrelated department, and have no inside knowledge / reads about what is going on with fuscia, and so my opinions aren’t more insightful than any other random engineer on the internet.
I'm curious how long Google!Android will be supported once Fuschia launches. Maybe 2-3 years, and it depends on how many existing Android devices can move to Fuschia.
Android's strength over Windows Phone was the app ecosystem and I don't think an emulator will instantly be good enough to emulate all kinds of apps with sufficient performance, especially games.
Amazon really tried to make FireOS work as a google-free mobile OS, but just never got the volume. Ok, I guess they still sell those $50 tablets or whatever, but millions of Firedroid devices is still a rounding error compared to billions of Google Playdroid devices, or even hundreds of millions of Baidroid devices. Network effects dominate - even Apple has a hard time with maps for exactly this reason.