catpower1980: Interesting that you say so as from a genereal European point of view, the US federalism is seen as something that always have been the rule, like: "there was the civil war and then boom USA as we know it nowadays was born" ;)
Actually, I would have a hard time imagining an US state trying to get back its sovereignty, seems like science-fiction :o)
Regardless of how one feels about federalism, Reconstruction was a failure in every possible way, and illustrated that the North wasn't at all morally superior to the South, though I do have considerable respect for Lincoln. The South was going to attempt succession regardless of whether he stood his ground or conceded on the matter of slavery in new territories, but that's understandable given that the status quo wasn't advantageous for them in the ways that it was for the North. IMO, the only thing that would have morally justified the Civil War is a successful Reconstruction that had significantly improved the quality of life of the newly freed slaves, and healed the terrible rift between North and South that survives to this day.
That said, I don't think succession today is all that improbable. We are a wounded nation with a federal gov't that has borrowed far beyond it's means. As it subsumes more and more of the national economy, that economy becomes all the weaker, while at the same time the people who control the business sector are literally running it into the ground extracting value for the sake of short term profits. Something has to give, and fairly soon, I think.