The answer to that is simple, and has been used by other media (to the chagrin of fans of course). When it comes time to "kill" the game, make a final update to strip all such licensed material out of the game.

The companies that develop and publish games amortize plenty of things out into multiple years. That's why live service is so increasingly common. The same developers and publishers should also factor in that they might have to remove some assets when they want to stop providing active support.