I have only bought classic cars on the basis of parts availability so have sitting in my garage or barn a MGB roadster, A series Land Lover and a vintage Ford Mustang. There is only one part you cannot buy today for the MGB (heater controllers), you can buy everything for the Land Rover and you can buy lots more parts for the Mustang than were ever factory original. It's simple to come up with a reason why these cars survive with pattern parts suppliers and that's over 10,500,000 of these cars were built and lots are still running around. Small volume production cars have no hope of building a strong aftermarket parts industry. It's only ever going to be specialist recycling centres and bespoke solutions for the Supra Mkiv turning it increasingly towards a garage bound curio.
Toyota is a volume car company that sells largely metal boxes to the masses, the chances of them catering to a tiny niche is absolutely zero. Unless owners want to keep their cars forever, really they should be selling while the market is good. Classic cars are an era thing, and their appeal (and with it the cars value) is expected to die out as the old petrol heads die out. Todays kids will only know electric and petrol cars will be smelly museum pieces, the mechanics of the future will be armed largely with screwdrivers.