Did you mean curse? Not hardly. It helped establish the south as a competitive. The north used slavery to build it's infrastructure. Once it was in place and the factories up and running it was a liability. The south was approaching that point but not quite there yet.
As for the slaves themselves? They have a heritage to be very proud of. Their work built a nation both north and south just as Jewish slavery by Egypt build some of the marvels of the world. Who's skill and labor did it? :>} The end result in both cases was an advancement in a people that would not have came for centuries otherwise. Meaning slavery resulted in the very advancement in blacks. There would have been no George Washington Carvers without slavery. That is a fact.
Slavery as known in the south would not have lasted past 1890-1900. It would have went the same way as the Company owned Coal Towns. Technology would have made it a liability. For example once strip mining began Coal Towns quickly died. But forms of slavery also existed in the mines yes even state sanctioned. Wars were fought over it. Wars you will not hear about in school or read in many history books.
So now it's 40 years and not 20? Shall we try for 60 or 80?
I did mistype, I meant CURSE.