I would like to see this, at least something would be happening.
Honestly it'd probably be better off that way. Google has far too much influence and control.
Huawei found themselves on their own because of the ban, and decided to go for HarmonyOS NEXT. Probably they wouldn't come back to a "joint development AOSP" now.
Now if Google lost Android, what would happen for the others? Would they each try their luck with their own OS or would they try to go for a joint development?