I mean, the rate at which people are dying and becoming disabled due to covid can't be sustainable, can it? This country was running on fumes to begin with. Surely a country with an infamously terrible healthcare system, an economy that runs everything with as little margin for error as possible, and a government that has lost its ability to respond to any major disaster that can't be shot at cannot withstand this kind of catastrophe? What do you think things are going to look like five years from now?
the material resource tribute is something i think that gets lost when people imagine balkanization scenarios for the US. for example, chicago is the golden idol of The Great West. forests are logged, grains are planted/harvested, rivers are drained, and mountains are leveled for the markets she paints in her dreams.
to imagine the city, any city, as separate from its hinterlands is a delusion. the very second that NY, LA, Chicago or any other wealthy "enclave" cleaves itself from the bosom that feeds it (by severing any pre-existing risk management program), the tightly wound land use patterns of rural, extractive communities will snap. hell, the US has cut so many of these programs already, it's probably going to happen anyway.
older cultures make massive investments in rural infrastructure and community support, because it turns out that's cheaper and more politically stable than having to constantly fight, enslave, and terrorize the plague-ridden barbarians that feed you every time some group of them decides to tell you to fuck yourself instead of sending the grain.