I think they would have done, and I also think mores states of the Union would secede and join the confederacy after the initial question of secession was settled in favor of the Southern states.
The new smaller countries wouldn't have developed a transcontinental economy and might well be poorer.
No guarantee that they would have been poorer, they might have been wealthier. All that blood and treasure expended in trying to maintain independence would have gone to more worthwhile pursuits.
And a transcontinental railroad was inevitable. I've seen people allege that the Railways act of 1862 was just a payoff to Lincoln's powerful supporters in the railroad industry.
They were certainly given immense wealth to build those railroads.
Racial conflicts would make life in the Confederacy turbulent and hazardous.
That is an area in which things might not have turned out better.
That is an area in which things might not have turned out better.
While Eli Whitney was a northerner, he would naturally have tried to create the largest market for the cotton gin where the cotton was actually grown. Slavery inexorably would have become less cost-effective than machine cultivation and harvesting.
If the south had succeeded in leaving the union and become self-governed nation, they could have developed options such as trade schools or armed forces training for blacks, or expatriation schemes to Africa, the Islands or South America.