If the U.S. government continues down the same road as the Late Roman Empire in the West (debasing the currency, implementing wage/price controls, over-regulating, etc.), it’s not unreasonable to expect secessionist impulses here to increase. Something pretty dramatic would have to happen for majority opinion to swing in that direction, but it’s not unthinkable. Hyperinflation, conscription for an unpopular war, etc., could precipitate a crisis that breaks up the Union. I don’t see anything like that happening in the near term, but one never knows.