If we ever have a second civil war, it would more resemble Spain's civil war of the 1930s than ours in the 1860s, which really was not so much a civil war but a failed attempt at secession. The leftists had their strongholds in 1930s Spain, in the Basque and Catalan regions and in Madrid, but there were Falangist supporters even there. Ditto for the traditionalist strongholds. Even deep blue places like New York and California have substantial numbers of conservatives, especially out of the metro areas. Ditto for the conservative states. Texas, for instance, has a large black and Hispanic population, plus liberal strongholds like Austin as well as Houston and Dallas inside the Beltway 8 and I-635 loops.
Eventually it would degenerate into a geographical conflict as the opposing minorities in each venue were slowly wiped out or fled to more congenial environments. As the lines began to gel, the New America wold take shape. If we could hold it long enough against the globalists, it would emerge as a clear economic, social, cultural, and military power, while the Old United States, home to whiners, parasites, professional victims, and weaklings, would collapse under its own weight and be absorbed by some other globalist concern.
Of course, they would envy our success and pre-eminent position in the world, and we would face a constant battle for survival. Kind of like now ...