Talk politics.

Essentially, you're entirely correct. The modern state with its highly centralized bureaucracy and strong military monopoly on force underpins the world that we know. But I don't think a sufficiently large-scale economy on a global scale focused on cities can ever be meshed with environmentally sound future. And to put it very brutally, the people that advocate a population cull of billions always want other people to die instead of themselves, so that in itself is revealing, honestly. And the problems are always ones to be fixed by drastic personal changes somewhere else over the hill and across the water because modern Western urbanites can't endure the kind of hard and cruel and backbreaking lives our ancestors took for granted.

The worm of doubt honestly is in the details of transforming a hypothetical concept like that into a reality. It remains science fiction, and if even a limited nuclear exchange happens that is basically a giant kicking over everything in a fit of temper and would obliterate the old order, all right. Not for the better.