I’d say the specifications of the design should be made public domain after some time (say 5 years for high-tech and 10 otherwise) or if the OEM shuts down the factory.
It’s a bit unreasonable to keep parts in stock 50 years after the product was last sold, but if the designs are available any company can start a new run, or even just a guy with a nice shop. The big exception to this is silicon chips, there are only a few companies that can even make integrated circuits, let alone processors. Public access to designs might encourage competition though…
Piracy has always been a distribution issue. There are definitely greedy lazy people who will always want more for less, but the organized effort required for piracy only happens when fair access is impossible.