There are many ways someone could interpret this statement. Are you saying that slavery still exists? Just in different forms? Or are you saying that slavery from back in the day is still an issue needing to be addressed and reprimanded?
Certainly, slavery is a market-driven phenomenon. Without market demand for cotton, tobacco, and other 19th century trade goods produced by southern slave labor, the need for the production of these goods would have been diminished. While northern merchants distanced themselves from slavery, they benefited from and profited from slavery.