That will never happen.
First, software is always considered proprietary information. No company is going to divulge it’s proprietary software in case they happen to go out of business. Secondly, what are you going to store? Source code? Never happen. Give me your source code and I’ll modify it to remove things I do not like- subscription based hardware? Emissions controls? Etc. Then what, you inadvertently corrupt some safety feature and crash… No need to explain the liabilities there…
Store object code? To what end? That processing core is likely to go obsolete if it’s even a COTS version. If it’s proprietary modification of a commercial part, they also own that design and good luck procuring one after they go belly up.
Why should a vehicle be any different than any electro-mechanical device? I can buy industrial equipment that costs orders of magnitude more than a car and it doesn’t have any protections against that manufacturer ceasing operations and making it a boat anchor…