All products, every last one of them are end of life’d by their manufacturer.
Not really. Many parts are available form dealers. I have fixed too many cars to believe you. There are after market parts makers like there are aftermarket software companies like adobe and such.
Aftermarket is not the dealership. Yes you can get aftermarket parts for a vehicle after the company stops making them but they won’t be available from your dealership.
You said explicitly the dealer/manufacturer would still provide parts and that is just not true.