The “end of history” fallacy is to acknowledge radical unexpected events got us here, but then insist nothing radical or unexpected will happen in the future. That things will just play out like clockwork. They won’t.
If it's not climate change it would just be something else (though -- most of the falling civilizations in my link do fall at least partly to climate change. The sea peoples wrecking the bronze age was very likely due to that and mass migration)