It was on the way out.
The Industrial Revolution where machines could work faster and longer were going to overtake output of those areas just using human labor.
Problem is you can’t really start working to change the way people think about another human being (less than people) if you can still legally treat them that way. Unless they can admit they know they’re wrong, there’s really only one way to deal with people like that.
What? Take all their stuff at gunpoint, and burn the rest?
In a couple of decades, the law could have been changed without that.
As far as changing cultural attitudes go, the biggest difference is that in one area the population was more honest about its attitudes while the other was sanctimoniously hypocritical.
Maybe, 150 years after that, we are getting over that as a society--and maybe not.
Either way, the damage was done to the Republic, and the Federal Government became the one to routinely impose its will upon the States instead of the other way around. Now we see the result of that.