"How exactly would slavery "melt away" when it was essentially adding the equivalent of about $100,000 (in today's dollars) on average to the wealth of each Southern family."
Ignoring for the moment that it was such Southern wealth that the Northern power structure resented more that anything actually to do with the slaves themselves, let me address the arrogance of such thinking.
The institution of slavery in the North, where it began, slowly died out for economic reasons -- not because of some higher moral calling. The same economics would have eventually caught up with the South as well. It would take longer bec of it's agrarian economy and scope of slavery itself, but 20th Century modernization would have brough it's eventual demise as well. It is arrogant to think that Northerners were somehow better people than thouse in South and thus the basis for them not having slaves. That's simply not true.
Ignoring for the moment that it was such Southern wealth that the Northern power structure resented more that anything actually to do with the slaves themselves... What's wrong with resenting people who have acquired wealth almost entirely as a result of holding people in bondage?
The institution of slavery in the North, where it began, slowly died out for economic reasons -- not because of some higher moral calling...
That's simply not true. Slavery was prohibited in the Northwest Territories because the founding fathers recognized the danger of spreading its evil. That same "higher moral calling" resulted in the abolition of slavery (i.e. it didn't simply "die out" on its own) elsewhere in the Northern states.
...20th Century modernization would have brough it's eventual demise as well.
So you think the abolitionists and negroes should have just waited patiently for a couple of generations hoping for slavery to magically "die out"? I suppose that you also believe that the American colonies should have been much more patient with King George.