Ten years before it happened - - it seemed almost impossible that the only other super power, the USSR would break apart. From what I've read, the leadership in China is also concerned about this possibility if economic conditions turned bad enough.
- - - As for the Civil War - it is usually characterized as a war against slavery. Economist Thomas DiLorenzo who has written extensively on Lincoln refutes this. He wonders why, slavery (which increasing numbers of people opposed), was eliminated in most of the world without the kind of war that killed so many Americans . Investigate the subject, and you'll see that the union, not slavery was Lincolns concern. The agricultural south was heavily burdened by tariffs pushed through by nothern manufacturing interests. DiLorenzo quotes Lincoln (who was a well to do lawyer for the railroads). When asked if the southern states would be allowed to leave, Lincoln asked "But who will pay for the Union?"
Given the outrageousness of history, who knows what might happen. But, I wouldnt call this absolutely impossible. The fact that the subject comes up often on web forums now is remarkable though. - - -