To have a Civil War you have got to have two sides with Guns and Ammo. The other side, Liberal Snow Flakes, would not be able to handle the heat, or have the training or equipment.
It would be too much fun to go up against them, though, tear gas, non lethal, will empty the streets.
If they were stupid enough to try. I don't think they will try.
Not to mention that our military is mostly non-snow flake, and supports the Constitution and Law and Order.
We already have de facto secession of those cities. I for one refuse to travel to Austin, even though I live a half-hour north. And IMO the outlying red areas will end up limiting travel from those zones if they want to remain sovereign.