I can tolerate a market over-saturated with science-fiction. I don't think I can tolerate a market over-saturated with post-apocalyptic. They'd have to work a lot harder to set themselves apart if it starts to become like "just another zombie story" things get these days with the over-saturation of zombie love. I don't think a lot of creators today choose science-fiction "because its cool" the way they tend to do with post-apocalyptic and zombies. Science fiction is just a realm in which things are more likely to happen, so it's a natural fit for certain types of stories, much like fantasy. If you want high tech, sci-fi; if you want dragons, fantasy. If you want waste-lands, post-apoc... And while I like things like Fallout, that have honed the artform, I really enjoy the breaths of fresh-air post-apocalyptic stories like Enslaved: Journey to the West, and what Horizon: New Dawn is shaping up to be.

Though this opinion is based mostly on games, and a perceived notion regarding movies (as I don't watch many movies, but I don't want thousands of Mad Max movies running around). I haven't read a lot of post-apocalyptic books. That might be a richer medium, for all I know