[Wyrd bið ful aræd]

If there were an event catostrophic enough to cause the federal government to collapse, I would imagine that numerous state governments would collapse and de facto dissolve as well.

That said, I think the point being made is that rather than there being two distinct regions (north and south) at war, the conflict would be between towns, counties, neighbors, similar to the ARW in the rural south but more brutal. Instead of Virginia against Maryland, it will be rural Georgia against Atlanta and northern Maine against southern Maine. In very conservative states such as Oklahoma, the cities will heavily secured, besieged islands. In uber leftist states conservatives will be hounded out and killed. Balkanization at a human level.

[central_va]

I think you are wrong or perhaps only partially right. GA and NY are two great examples. The state governments will not go away or collapse, actually the opposite is true; unleashed from the feds, NY will go full on Commie and GA will go full on democracy/freedom. So there will be an insurgency in both states, up in NY “conservatives” will be the insurgents to be hunted down and rounded up and conversely the “leftists” will be the hunted down insurgents in GA. You cannot paint with broad brush.