The point here is that Windows Mobile has already solved this problem: All Windows 10 devices receive OS updates directly from Microsoft servers, as a requirement of using the platform. (Even in 8.1, if you were on Developer Preview, you got updates straight from Microsoft, apart from carrier/OEM channels.) Drivers/firmware are pushed separately.
This appears to be where Google is perhaps finally heading. Once Treble is out there, Google will change their contract terms to mandate control over OS updates for all devices which license the Play Store.