Slavery was nearly at an end, but then the cotton gin came along, so whatever came after would have replaced the gin and the need for slaves.
And just the vast numbers of blacks would have prevented an SA
Slavery would have come to an end, probably not latter than 1900, not because it was profitable, but because of the engrained cultural tradition. But for that cultural tradition, it would have ended at least 20 years earlier. Segregation is another matter entirely. Segregation would have continued well into the 1960's and 1970's, if not longer and would have been quite similar to SA.
I mildly disagree. I believe if slavery had been allowed to die a natural death as it did in Canada and Mexico, segregation would not have been a natural consequence as it did not occur in Canada and Mexico. When social change comes via the conscience and more noble intentions of the people, the results is almost always more edifying and satisfying than it is when it is via government edict and most especially when it is without a bloody war that created many long lasting problems apart from the issue of slavery.