Your copper line goes all the way to the exchange, it never becomes fibre as an individual line and never will. It will either stay copper or become voip over the fibre to your house.
I was thinking it was like that but wasn't 100% sure.
So when full fibre arrives we won't have one line that goes from the customer to the exchange (?), so we won't be able to complain about a faulty line, as it'll be just fibre to a network?