There will be no civil war. That is as ludicrous as some of the other discussions. There would have been no first civil war had it not be entirely, 100% regional. It was a fight over an economic issue (slavery), a power issue (white over black in the south), and, yes, a constitutional issue (state's rights---but ONLY the right of whites to own states), and above all a property issue (what is the definition of property, i.e., can a person be property). However, all that said, there would have been no civil war had this not been entirely demarcated along sectional geographical lines, because if you had had spots of slavery (i.e., "slave counties") in the north and south, without the power and resources of states behind slaveowners' enforcement mechanisms, it would have eventually died out.
There is no such regional demarcation in the US. Even the old "red/blue" doesn't work, because states such as OH and MO voted for Obama. And even in regional bulwarks against liberalism---North Carolina and Florida---you now have heavy Dem turnout.
A rebellion by TX and, say, ND would be crushed in a heartbeat.
A civil war is a pipe dream.