That would be amazing.
Personally, I want a way for any player to re-do their Generation quests (namely the final boss fights of each) and be able to instance raids/dungeon bosses.
For example, there could be an option at the Crystal Ball in Dunbarton library to "Replay Generation" or "Refight Boss" for the Generation quests... the other dungeons (not just Ciar/Rundal) could get Boss Trial passes (even for Abyss bosses - Duke and Sephirot), the Iria dungeons could get special "Boss Rush" artifacts to use instead of passes, and perhaps a new area could be added somewhere (maybe the gate of Metus?) for players to confront the raid bosses directly (solo play would have less/no 'army' spawns in the case of White/Black Dragons).
It would certainly make getting transformations easier.