The fan theory that the Jetsons and the Flintstones are actually contemporaneous to one another -- the Jetsons' sky cities being the land of the wealthy (or formerly wealthy, perhaps, since capitalist wage relations still exist, even in a world with literal robot servants) and the Flintstones being the descendants of the poor people who couldn't escape to the skies when the world fell apart -- is starting to feel less like an amusing diversion and more like a prediction of the future.