Many people still refer to the civil war when these topics arrive on the scene, although the civil war definitely taught us a lesson about secession. It is becoming clear that our unity is not as strong as before.
Despite 9/11, the cold war and our history of trying these things before our diversity is playing against us. When the dollar finally gives way the United States is going to head for a collapse, which will likely result in martial law, high taxation etc will only discourage states from remaining part of the union.
A revolution will require the unification of the many diverse, powerful and large non-government political groups in order to take down the powerful federal government. If peaceful protests turn to violent conflict (like what we saw in Syria) then we will probably head towards a messy civil war. Although it would unite the groups (much like what we saw in Syria) more than ever we cannot leave out human nature, and our violent culture. These two things will likely start creating politics between the extremely diverse groups which will turn towards each other once the dust settles.
We cant forget that extremism tends to gain attention during times of crisis as well. The desperation of our already war-weary and bankrupt people (if we get to that point) will have to potential to drive many people mad.
When the national government is bankrupt, paralyzed, and stuck in a messy war many "average joes" will likely begin to rely off their local communities more than the nation for survival. When your community begins to share your beliefs, and keeps you alive you tend to feel more love towards your town than the nation. This is called "local-ism" and in times of these it tends to rise out of a need for survival and protection. Localisim (in this possible scenario) is likely to refine the "micro-cultures" within the United States, and create more love towards smaller, regional governments rather than the national one.
Although it would totally turn all our lives upside-down, create a horrendous political situation, possible poverty in states full of people relying on welfare and years to sort everything out this scenario is fairly likely (given the right circumstances) to rise. How I see it is we will look like Syria for a while, then the kingdoms after the collapse of Rome, then the EU (with the possibility of reunification some time later). All I can say is humanity, America and the world is in for one hell of a bumpy ride.