That's a little different, but an interesting topic to discuss!

In my opinion there are 3 ways forward in such situations.

1. The manufacturer designs the car so that the infotainment unit is replaceable when they stop updating the original. Replacements not certified as "road safe" would be illegal to install.

2. The manufacturer literally never stops updating the software... (yeah, obviously this isn't a real alternative, but it's technically acceptable if a manufacturer wants to attempt to make that promise)

3. The manufacturer, after ceasing updates, provides the necessary documentation for an alternative software to be built, but it wouldn't be obviously legal to install just anything, the software would need to be certified "road safe" and how you would assert that you're not running unsafe software is not obvious to me.

I don't know why my infotainment system modifications would need to be certified. The head unit itself is swappable with something that just runs stock Android.

(I don't swap it because there are a few minor annoyances with that)

Because there are laws about what a driver is allowed to do while driving and for very good reasons. Infotainment systems are a natural source of distractions, and without safeguards there isn't anything stopping things like Netflix from running while the car is being driven.

I wish we lived in a world where we could say, "sure but the driver knows not to put that on while driving, so we're all good!", but we very much unfortunately don't...

I can mount my tablet and run Netflix. I don't think one needs to restrict what software I can install when it's already illegal to use it while driving.

Hell, I could pull a small grill into the 12V power supply and cook dinner while driving down the road.

The idea that software can police our lives is actually part of the issue we are talking about. Apple doesn't want us to be able to install arbitrary software on our phones "for our safety".

That's a fair argument, you've honestly swayed me.