AOSP isn't dead, but Google just landed a huge blow to custom ROM developers
(www.androidauthority.com)
or a brand whose phones support their requirements other than google.
Wasn't Graphene's "selling point" for long being that nothing but Pixels can match their reqs? I don't see why any current band would want to make it easier for them, and I also don't see new brand significantly entering the market.
Graphene boiled themselves in their own frogpan.