> "Carmakers, please find a way to separate the 'infotainment' part of the car's computer from the embedded computer that's actually required for the car to run"

They have, sorta (but it's still rather limited in functionality):

https://www.android.com/auto/

Android Auto and I believe Apple Car Play both run totally from your phone/tablet, with the car just being a view screen. Thus, you get updates when your phone updates.