steve59p
I suppose a little clarification is need on my part. The reason I say a World War would be possible is because of the tensions that permeated Europe in 1914, existed to some degree, for example in 1860 some in Britain were suspicious of France, (they were a minority), and Britain was very suspicious of Russia regarding India, the Austrian Empire was suspicious of Prussia, Russia, and France, and vise versa. Everyone in Europe had their own designs on other countries, and if Britain had interfered in our own CW, those "suspicions", and "designs" could have erupted into another European war, and with war in North America, Europe, India, and Southeast Asia, such an event could have been called a World War, not on the scale of the 1914-1918, but a World War nonetheless. I would call it comparable to a mixture of the American Revolution and WW1, not identical, but a cross between.
On the subject of US and CS relations, a long term war to create a mutual hatred similar to pre WW2 France and Germany was completely unneeded, for that had already happened culminating in the South's War for Independence, and one section successfully seceding from the Union would have driven the US to keep the fight alive politically not just to eventually reabsorb the now-independent CSA, but also to prevent any other states from breaking off from the Union.
As for the Confederate populace I think a honeymoon period after the conclusion of the war, and the economic, and political divisions of the CSA would have disappeared, until a great national calamity, like the Depression of 1873. Such a calamity coupled with State's Rights, the planter class's control, and States like Virginia and Georgia asserting themselves above others, (which was a major problem in reality), would have created a true civil war, and the USA would have undoubtedly invaded to re-absorb the CSA. An invasion of the CSA by the USA in such a time period would have galvanized the Confederacy into straightening their act up and re-uniting to meet the mutual threat.
Now France after the Franco-Prussian War was deeply in debt, but immediately afterward began a program of rearmament anyway, and was looking for ways to show they were still a force to be reckoned with, thus why I can see a CS Civil War with a US invasion beckoning to them. Plus in classic European practice, they would have made it clear to the CSA that it was indebted to them, which would result in a binding, basically permanent alliance, that would favor France, thus transferring the debt from the Franco-Prussian War and the hypothetical CS Civil War to the CSA, which would preclude any and all territorial ambitions the CSA, and leave them, plus the USA through their defeat, third rate powers until Spindiltop.
As for the French Intervention, I can't see France being involved there past 1866-1868, because in reality it was clear to even Napoleon III that it wasn't going to succeed, and after just finishing its own War of Independence, the CSA wouldn't have been in a position to help them. In reality France saw the writing on the wall in 1866-1867, and just used Seward's threats as excuse to leave with their honor intact, to some degree, plus the French populace was already fed up with it and ready to overthrow Napoleon, even before Prussia came knocking, and Mexico had become an albatross for the Imperial French Government.
But you have some great points, in the end this is all a "what if", after all