Some big parts of why we subsidize rural areas is 1) an emergent property of allowing people to live where they choose and providing a base standard of living for every community, and 2) romanticism for our pastoral past, and an implicit belief that societies should provide the opportunity sparser living with more exposure to nature.

I don't want to brush off these aesthetic concerns as "wrong": the 100% urban megalopolises of science fiction always carry at least a tinge of dystopia, because a desire for nature and open spaces is to some degree hardwired in us. But they have nothing to do with what we're talking about, which is sustainability.

The kind of robustness you're talking about doesn't have a whole lot to do with the urban/rural divide. It's entirely possible to have an almost-universally urban population and still maintain domestic food production, either by changing agricultural practices to fit cities better or at worst by having a "skeleton crew" instead of entire communities (the number of people living in sparse communities right now is _far_ below the minimum number of people we'd need to grow food).

Again, I'm not suggesting we do this, or that there's a clear path from point A to point B. I'm just illustrating how your point is a non sequitur.

Because again, despite what people seem to think, smaller towns rely a lot on cities as part of their supply chain for things such as medical supplies, gasoline and infrastructure. Isolated farms are not self-sufficient no matter how much you may believe it to be so, because once the power runs out, once the water stops flowing and the supplies stop coming in, said isolated farm is far and away from other natural resources that are rather important for farming and survival.

I'm wondering if people have ever been to the midwest?