I don't think it will take as long to level from 50-60 as it did from 1-50 but I also don't expect it to be done in an hour either. It will probably take half the time if I were to guess. They'll probably want you hitting level cap by the end of the expansion main story just like 2.0 and I don't expect the expansion story to take as long to complete as 2.0 either.