I secession rears it's ugly head, we're likely see that. And rape. And murder. And starvation. And orphans. And disease. And all sorts of other stuff that civil wars tend to bring along in their wake.
This isn't 1865. Civil war won't move at the speed of the telegraph.
Besides, there are many more people here from other countries. Most of them are permanent residents, and not citizens. What would the foreigners do, take up sides or go home?
Are Indian programmers going to fight for Obamacare?
Will the white middle class sit still if this "civil war" is mostly poor inner-city blacks and Mexican illegals fighting to take over the country? Many would see that as "invasion," not "civil war."
I don't think you can evoke 19th century or third-world images to cite how a "civil war" would play out today in the United States.
-PJ