As to a civil war? I don't know. I can think of three situations where one might happen.
All the bigots, crazies, and Tea Party types running around keep threatening to rise up in a revolt, but they would surely lose. Their war would be with the entire structure of the American government, and basically to secure lots of freedoms for themselves and to destroy them for anyone else. It's not righteous and they would be completely alone in it.
Keep kicking the poor so much and they might rise up, and they would have a legit cause that a lot of others might take up. Nothing like desperate times to make people take desperate measures. I don't know if they would be alone in their actions. A lot of people feel that great injustice is being done to the poor of this country, being kept off the social ladder, with no means to advance. But I don't know if they feel that way enough to take up arms when they are not affected. It could go either way.
The increased militarization and "security" of our country might continue and lead to real fascist policies, which could lead to a revolution against the government. That one would be a lot trickier to win, since it's the scenario where there would be the greatest divide between government and people. The former has far more resources. That's the revolution that the gun folks want to fight, but it's the least likely to happen, and also probably the hardest to win, since we would be that much further from a free society by then. Rather than fight it, I'd rather stop it from coming in the first place. I don't see how any political ideology can include more surveillance on people, searching people and invading their privacy. The government should not be in the business of spying on people, not with cameras, not tapping our phones, not reading our e-mails, not scanning our bodies at the airport, nor stopping and hassling us on the street without cause.
Either way, change will come slowly, and slow change is a pretty solid deterrent against drastic actions. I don't think any kind of revolt or civil war is likely to happen.