> It would be quite ironic if, after all those changes, the words “primary” and “secondary” would simply become the synonyms of “master” and “slave”.

As in, to describe actual human slavery?

Most English-speaking countries don't have actual human slavery any more (or at least, they don't use the words master and slave to describe it.) So when using the words master and slave to refer to actual slavery, it's usually in a historical sense, and it seems unlikely that we'd change the words we use to refer to something in the past.