Can you IMAGINE the propaganda against a seceding state? About the “poor oppressed minorities and political dissidents?” All the pro-war movies that were not made during the current war would suddenly be in production. We'd have all sorts of movies with the heroes killing droves of drooling white bigots (that's how the see us, ya know...). Editorials would demand war on every show and in every issue of every paper or magazine. It would be ugly, to put it mildly.
No. Its pretty much certain that the will would exist or be manufactured to go to war against a seceding state.
I'm not sure I agree on this. It's not popular because war, in this day and age, is not popular. There's rally around the flag support, but that tends to disappear pretty quickly.
But, this is likely all speculation, at least for the time being. Even as the most pro-secessionists amongst us would concede, such an option is a long, long way off. It's fairly useless to try and read the political winds of ten or fifteen years down the road.