I don’t get the geographic/demographic analogy. And this is 100% coverage, not a regional area. This will be a different sort of civil war, less regional. We are all mixed together. It will be racial, religious, and urban v. rural. More like Bosnia and the French Revolution and the Cromwell years than the American Civil War or the Revolutionary war.
The analogy is just political.
Or an out and out insurgency like Iraq (only more nationalistic than religious).
Right now you are correct, but the states that are starting to assert their independence are mostly conservative. If nationalized HC doesn't get stopped in the courts or in the legislative it's not far fetched to see a time 10 years from now when southern states want out of the union.