The beauty of open source is that Google can't take it back. The worst they can do is close source their own future development. Meanwhile, the community can fork the last open source release of AOSP. Look at what open source devs did with Audacity, for example.

The real fly in the ointment here is Google already did with device trees and driver binaries for Pixel phones; no longer sharing these with AOSP will have a very chilling effect on custom ROM developers who must now reverse engineer needed configs and drivers.

I’ll worried for GrapheneOS because I know the dev doesn’t really want to implement QoL improvements or design updates, so we’re currently only relying on Google's good will with AOSP for that, and we can’t expect much I’m afraid

Don’t get me wrong, GOS is good and all, but some nice features are bugged or getting killed. It might be worth delaying casual updates to fix those

Now we have a new threat: no more third party stores. At this point iOS would even be better, at least there’s some very limited sideloading

You can currently sideload a bit on iOS, but it’s a massive pain

There's still a surprising amount of devices made by HMD (who own Nokia's consumer phone brand, so you'll sometimes see them as Nokias) that run Series 30+ (think old Nokia software with some very slight modern enhancements) but have 4G hardware to play ball on modern networks.

I really want PostmarketOS to succeed, even to be good enough as a secondary device. The long term support and software flexibility seems so promising, but it is still nowhere near ready for most people.

It is absolutely a fork.

Yes, that is what a fork is.

Users don't matter. They are making more money than ever.