Already, around 5 years ago, I had a small repair (tranny fluid filler tube replacement) done at a transmission shop. When I arrived, I walked in to hear the owner cursing Ford, because the part required for a 10-year-old Mustang was no longer made by Ford, but also not yet made by any aftermarket. The shop had to custom-fabricate the part themselves.

This will only get worse. Look at how many smartphones don't get security patches after 2 years.