All in all, I think that they'll just stick to GV and Copen, addition of more characters would stretch the uniqueness of each character. I think it would be intresting if there was no Awakenings till the very end of ASGV3, then you would unlock them after GV/Joule and Copen/Mystyl met again. Or Mystyl could be Copens final boss, and GV could have some story that doesn't parallel Copens quite so...