So you think that Industrialization has taken away the need for slavery? I'm sorry, but slavery very much exists today, it's just not out in the open. Sweatshops are the modern equivalent of slavery. People are sold in 3rd world countries everyday. But the difference is that most countries actively try to root out such practices.
I do agree with you that, historically, industrialization made it easier for nations to end slavery, but I also think human morality plays a huge role. As the world becomes more educated, there is a steady progress of individual rights and worth. It may seem slow, or even going backwards on occassion, but overall the world is becoming a better place.