Most of those forks twiddle a lot of low-level knobs, and if Google does not want to support those then the forks will have a hard time anyway.
The big problem is that aaaaaalll these forks are still just a tiny tiny tiny drop in the bug mobile phone OS bucket.
If the forks want to be sustainable they need to cater to the market a bit. (Of course that's much harder said than done, but we see - for example with Nothing Tech - that there are new successful upstarts from time to time.)
However, Google might have planned to slowly make Android proprietary, which means death to 3rd party forks.