I know the argument being of Southern stock and having lived in the South a number of years. It was about state’s rights according to my family. Slavery would have ended at some point peacefully. Maybe, maybe not. But it was really about slavery; Lincoln was an abolitionist and the South expected him to free the slaves at some point. In some ways it was a clash of civilizations.
As for what would have happened had the South won, I don’t know...we never will. But, how can one expect that a government based on the enslaving of one group expect them to extend liberties to another? Thus, I don’t believe those who claim it would have been a freer society are correct...it’s romanticism of the gallant South that makes people believe this.
I agree that slavery would have ended at some point. Slavery was an expensive proposition in that those enslaved really weren't interested in working and the cost of their care, e.g., clothing, food, et al expenses. Couple that with the fact that we were on the cusp of the industrial revolution and one could easily predict slavery's end. The cotton picking machine, for example, requires only fuel, oil and occasional maintenance. And, it doesn't create any social problems.
As for the remainder of your missive, all I can say is that everyone is entitled to their own opinion however erroneous it might be.