You are fantasizing. Slavery was always a bone of contention in the United States prior to the Civil War, and moribund, regardless. It would have ended in a generation or two without the War. Certainly those who opposed slavery most fervently clearly did so on moral or ethical grounds. In fact, most Northerners knew that ending slavery would be a net economic loss to themselves: the price of tobacco, cotton, and other crops would increase. (John Calhoun’s Nephew, one of many anti-slave Southerners, pointed out that the Northern Hay crop was economically more valuable than Southern Cotton, and that cheap slave labor suppressed poor white wages in the South.)
Economic benefits from abolition would flow almost solely to former slaves. The cost of the Civil War was enormous for both sides in terms of blood and treasure. The war is romanticized today, in some quarters, but it was Hell for those who experienced it.
In the slave-owning states, it was possible for middling folk to set themselves up as "lords and ladies" so to speak. A sort of gentry class that they never otherwise would have attained had they not had slaves to do all the domestic and farm chores for them.
For them, the ending of slavery would mean that they would lose that status and become mere employers at best. In fact, most of them would need to reduce "staff" significantly and take on much of the actual work themselves. The ladies would have to get off their couches and spend time in the kitchens. The gentleman would need to get off their front porch rockers, roll up their sleeves, and get their hands dirty for field and barn chores.
People don't like to talk about this aspect but the prospects of losing their status as "masters" and thus getting moved down the social ladder accordingly horrified many of them.
Actually, Lonesome in Massachussets, it was much cheaper to employ Irish immigrants than to keep slaves. You damn Yankees could just fire them and let them starve in the streets when they weren’t profitable. Which you did.