I think as a state policy yes. But there are a lot of variables to take in account. For exemple, in Brazil, in 1888 when the slavery was abolished the government did not creat policies to become possibilite for the black people from that moment on "brazilian citzens", to live in society with the same rights of the white people. So, the abolitionist official policies must be followed by public policies to insert the old slaves/new citizans in society with the same rights that free people had have already. I believe that a "truly abolition" can happens just in a mid-term with policies to equalize the relation. If not, the problems of the slavery like racism and unequality between black and white will persist for a long time.

I agree that racism and extreme inequality in a way are related to the hierarchical conception of society and therefore to slavery.

I think that yess, it is, but not as much as before. The Connvention on Slavery of the League of Nations of 1926 is an important step toward the effective abolition.