Google develops Android and thus is responsible for it's update scheme. They already changed it quite a bit in the last years with GSIs and Project Treble but there's still no real seperation that would allow the same drivers and hardware blobs to be used independent of the Android Version or updating the Android version without these needing to be included every time.
That's what needs to change.
But Googles decides, that that is possible. I fthey changed the structure to enforce a seperation there's nothing that would keep Android updates from those devices. Put all hardware and device specific stuf in a seperate layer and have it accessible to the updatable system. And it's not like these vendors have an alternative to go to