I for one see more dystopian scenery originating in the hell-bent overpopulation we've been witnessing on the planet for the past 100 years or so. We're looking at ~1'000 places with a population of 500'000 up to 37'000'000 these days (source: https://worldpopulationreview.com/world-cities); they comment, quite correctly IMHO: There are quite a number of popular and culturally rich cities that have smaller populations, often making for higher living standards for their residents. Barcelona, Sydney, Berlin and Vancouver all have fewer than five million residents, but are very popular choices for city living. There are also some comparatively very small cities with big cultural, historical or political reputations, such as Sarajevo (314,000), Edinburgh (502,000), and Venice (631,000), demonstrating that small cities can be highly significant regardless of the size of their population.
For almost the entire history of mankind, one million people in one place was a singularly big place, and non-existent as recently as maybe 3'000 years ago (personal estimate). Mankind must learn how to live with a shrinking population. I hope figures will cap out at ~10b people as predicted by the UN; after that, I consider ~1b people as a goal, that's the figure from 1800, so 200 years ago. Even when I was born in the 1960s we had but a paltry 3 .. 4 billion people on this planet and we made it to the moon for heaven's sake. Should be good enough, right?