Yes, it will never richly tone again, at least not in our lifetime! It may go brown like a piece of old copper pipe, one day, if you're lucky? Highly polished surfaces need micro-corroding, for want of a better word, to hold a nice patina. It's virtually impossible to reverse a polished surface for toning! As everyone has said, get rid and start again, it really isn't worth faffing around with it, honestly!