Cars are harsh environments with heat, moisture and vibrations. Automotive electronics are considered heavy duty compared to consumer electronics, but are still rated for about 8,000-10,000 hours of operation.
One way to think about it is that temperatures inside a car left in the Arizona heat can easily reach 160. Inside the engine bay, they can easily reach 200F.
Now, if you leave your consumer electronics inside a car every day during the summer, you can expect a significant proportion to fail. For instance, your lithium batteries in your laptop are going to have a bad time if you operate them over 113 and they will start getting damaged when operated over 100.
https://www.apple.com/mz/batteries/maximizing-performance/
But you expect your computer modules to take it, and they have been built in such a way to take it, as well as all the vibrations, moisture, and temperature swings of a car. You can leave your car in the street in the summer, walk back into it after it's been sitting in the sun, and apart from needing a steering wheel cover you can start the car and drive away, with all your modules working. And you can do this for a decade. It's pretty amazing. How many people have gotten the "phone is too hot to operate message" when leaving their phone in the car in the summer, but their infotainment screens continue to work? It's happened to me all the time.
If you drive 2 hours a day on weekdays and one hour on weekends, so 12 hours per week, then that is 6240 hours of operation in a decade, so expect your car electronics modules to start dying around year 13 of use, and by year 16 of use, you are past the point for which these modules have been rated.
The infotainment screens will last 7-10 years.
Sensors in the engine bay will last 5-10 years.
The problem is that people expect their cars to last 20 or 30 years, and they should be able to, but cars weighed down with electronics are going to last only about 10 years. That's a huge problem for people who will get saddled with massive depreciation. If you paid $70K for that car, you are going to lose it all over 10 years, that's $7K depreciation per year (on average) but of course it is front loaded as you will lose 40% of that in the first 3 years.
So the software defined car, is going to radically change the economics of car ownership, and how much automakers can charge for cars, or equivalently it will dramatically shrink the pool of people who can use a car.
Now, you may think "I will escape this and just lease the car", but that is just a financing arrangement does not allow you to escape depreciation, as you pay for the depreciation in your lease cost. You can say "I will escape this and take an uber or taxi" but here, too, the depreciation costs will be passed onto you as a customer. You may think "the automaker only cares about the first buyer" but the first buyer is the one that absorbs the vast majority of the depreciation. There is no escape.
I don't think people have internalized the financial horror that is the software-defined car. The average age of a car on the road is now 14 years. You are talking about transitioning to cars that will only last 10 years. It's going to completely shock both automakers and car buyers.
What will happen to your iphone-defined dash in 10 years, when iPhones use completely new protocols and are not usable with your car anymore? It's one thing when it was just infotainment, and people could install more modern aftermarket units, but when the entire thing is integrated into the dash and controls critical functionality, then this will turn into a nightmare.