IC: Well, if the South secedes, I think it was readily apparent, even by this date, that the power that the South had held was no longer so important to the Union. Maybe the North would have kept along its merry way; after all, cotton prices fell shortly afterwards. Without soybeans, the South is nothing.
I still find it amusing that the South's agriculture was only saved because a guy really, REALLY wanted to get away from his father because he hated the old man. Talk about your For Want of a Nail. I wonder what Grant would have become if he'd stayed in the army.
If there is secession though, which states would secede? I can imagine South Carolina, Mississippi, Alabama, Georgia and Texas might...Louisiana and Arkansas too?
And what would happen to Robert E. Lee? I mean, he's well known for going back into engineering and helping both the Northern Pacific and Southern Pacific build their transcontinental railroads, to the point that he's a playable character in Railroad Tycoon 3's "Northern Transcontinental" scenario, but would he be caught up in the split at all?
You know, it'd be really funny if Lee, who was supposedly one of the greatest soldiers in addition to being the greatest engineers of all time, wound up serving against Grant, the other "potential" soldier. Grant's views on military matters were evidently some of the clearest and most concise of their time, so who knows? If the South somehow survived the Young Napoleon I can't help but think that maybe things would have ultimately wound up *that* weird.
It's also weird to consider that Louisiana's Greatest Governor Ever, Braxton Bragg, would probably have gone into the war. It would have been a waste of a good administrator to have him serving for either side.

The man was the greatest Louisiana governor of the 19th Century and the one that made this state the commercial center of the modern South.