The fucked up part is nowadays third parties like banks or sometimes even governments make apps rely on Google services, so you can't use an ungoogled phone for stuff you actually need for life...

I guess if Google closes down AOSP it would get forked, and the fork would probably be a separate thing from the current Android distributions. So that the landscape would continue to look a bit like today, except that AOSP would be an independent thing.

Then I guess it's possible that Google would seek to make android apps incompatible, gradually making the whole thing kinda pointless. I can't say I'm using Android for the great UX - I'm using it because it supports a few apps I continue to be forced to use. If I can't use them on Android any more I'm switching to Ubuntu Touch or PostmarketOS in a heartbeat.

right! I never understood why isn't there more cooperation between different foss roms, at least sharing patches and coordinating some work.