There is an old fashioned belief that the western world could seriously challenge itself on the question of slavery until it reached a stage of technological development where slavery was no longer a viable economic model.
Marxists made up a significant chunk of these believers. I wouldnt press this belief too far, but there is an element of this hypothesis that sounds particularly relevant in the age of animal rights.
Industrialization made the demand for low-skill hard labor too weak to bare the slave market through the end of the century. The cost of offense taken by a witness to slavery could, less and less, be rationalized away as a matter of economic necessity, and the mechanized north turned against its southern neighbors, and decided their way of life was no longer in line with modern moral sentiments.
With the advent of low-cost, plant based meat substitutes and the general decline in human deprivation and starvation, the possibilities of a new moral revolution becomes possible.
This issue, as far as anyone can tell, is unlikely to warrant a civil war or large scale violence between humans (against animals is already the norm). But when the inevitable conflict truly begins to heat, it will be the city dwelling "libtards" against the "unsophisticates," so Roger Stone calls them.
The current divide deepens.
And a moral landmark is planted firmly in the ground.