Slavery largely dropped away after 1865, when chattel slavery ended in the United States. But it came back on the rise again somewhere between 1970 and 1990, and, in the last few years, there is more attention, and it is probably going down again.
It would be wonderful if chattel slavery (legal ownership of one person by another) ended completely, but that is unlikely Governments are becoming less functional and more corrupt and oppressive. Powerful people are greedy and enjoy control, and being slave-owners fulfills those desires. So I think that there will, unfortunately, always be some slavery going around. May it be less and less.