user14111 commented in another question about a story which I'm unfamiliar with, but would like to read:
Reminds me of a sci-fi story I read where earth is contacted in the future by powerful space aliens, and they've been watching all of our old Star Trek shows, and the shows have stopped coming, and the aliens are here to demand that we produce more of them, or else.
I believe I read it in a magazine, like F&SF or Galaxy maybe, sometime in the 60s or 70s. In the story, the Outer Space Trekkies' ultimatum causes frantic research into TV history, because Star Trek is long forgotten on earth.
While it reminds me of elements of Galaxy Quest, I don't have any other ideas on where to look for this story.