This is not easy to do when the owner of a game's "intellectual property" is willing to defiantly sit on it as a game slips into obscurity and then abandonware. It's the intangible version of the real estate phenomenon of huge parcels of land that sit barren in (sub)urban areas, sometimes for decades, while its speculative owner waits for that Deal of Lifetime.
Copyright straddles and strangles that preservation goal like a Berlin Wall.