We all love to hate on the Confederacy . . .
But have you ever heard of Serfdom in Russia?
Slavery with some different terminology and it was abolished around the same time, in 1861.
Antebellum slavery was just an institution born from a inherent need (cheap labor) that would have been peacefully replaced and phased out in time as technology and society progressed.
Just like Russian Serfdom.
To add to what has been said, the American Civil War was as much an ideological conflict as it was an economic one. I've already spoken about the development of a thoroughly pro-slavery ideology in Southern circles in my first post here, so instead I'll limit myself to just the immediate pre-war situation. The South so despised the 'Black Republicans' and were so paranoid that Lincoln would discard their Peculiar Institution that even before any fighting or secession happened, they fractured their own party because the Northern Democrats weren't sufficiently extremely pro-slavery for their liking - ironically almost certainly dooming both Democratic tickets to defeat - and Lincoln himself was not even allowed onto the ballot in any of the future Confederate states except Virginia.
Imagine that. At least in modern California, you can still vote for a Republican candidate if you want, though they're exceedingly unlikely to get anywhere outside of the rural hinterland counties and maybe some suburban ones like Orange County. In 1860? If you were a Southerner who lived anywhere outside Virginia, you literally couldn't even vote for the Republicans, because they wouldn't have been an option on your ballot.
That is how much the South feared and hated Lincoln. (Incidentally his predecessor in 1856, John Fremont, was similarly not on any Southern ballot, not even Virginia's, and threats of secession if he was elected were also thrown around with alarmingly casual regularity in that election too)
I don't believe a society that willing to shoot itself in the foot just because their compatriots weren't as zealously committed to slavery as they were and to openly shit on the democratic process (just as if not even more brazenly than Lincoln himself would in the war with measures like the sidelining of
habeas corpus), had it emerged victorious in the ACW, would have forsaken slavery anytime soon even if they couldn't (or refused to) find new and more profitable uses for their slaves, like those
@Abhorsen suggested above. Not after they'd even more firmly wedded themselves to the Peculiar Institution with the blood of tens or hundreds of thousands of Southern soldiers, depending on when the war ended.
And the generation of poorer, more populist Southern leaders who came after the planters were
more prone to upholding white supremacy & keeping the blacks in (as close as they could get to) slave-like conditions with murderous violence than the old planters, not less! 'Pitchfork' Ben Tillman and Theodore Bilbo, for example, were vastly more thuggish, bellicose and dishonorable than the likes of Lee and Longstreet, after all - even comparing them to NBF would be unfair to Forrest, they seriously acted and sounded more like William Quantrill or 'Bloody' Bill Anderson (or any other of the CSA's most disgusting & sadistic commanders you care to think of) in governor's chairs than they did the founder of the KKK.
Think of it this way: the Soviet Union didn't abolish Communism after the Russian Civil War, no matter how much economic sense it made and even after the fanaticism of the earlier wartime generations gave way to those of more pragmatic and openly, indefensibly corrupt apparatchiks. So I believe post-war Confederate society would have followed a similar trajectory to the Soviets as far as defending an economically inviable and morally monstrous system goes, unless they're absolutely militarily forced into abolishing slavery by the British or another foreign power (against which they had far less defense than the USSR did against its fascist and capitalist enemies).
