Oh definitely. Half the US military against the other half? That would be scary.
But I don't think the real power in the states would let it happen. Bad for profits. I remember Chomsky talking about the end of the Vietnam war being decided years before the marches and Kent state, etc. Similarly Nixon getting the shove for pissing off only half of real power in the states (Chomsky again).
I not sure how much leverage Trump has in this stuff. His poll numbers are excellent and he could win the next election. But civil war to save himself? Debatable.
There's actually a really good movie on this subject called Bushwick (2017). It's an action movie but the end is interesting.