I believe that the best way to advance into other dragons is through more personal story.
Living Story seems so small scale(just doesn’t feel like a Main Story for a game) in comparison to a personal story because it is simply not personal enough. The instance with the Bloody Prince was probably the only thing that presented story. Of course if you go to the Mad Realm you can hear the Mad King and The Prince talking about past happenings.
Single player content sounds contradicting to an MMO but IMO players like to be alone sometimes and be able to complete stuff on their own. I myself don’t like to rely on others in dungeons, but it is simple, if the players are bad I just leave the group or be patient if I see light at the end of the tunnel.
The personal story is the best kind of content for lore and main story. Extending it to fight off the other Elder Dragons would be better than to just putting the dragons on a Living Story piece. It allows the customer to repeat the content if he/she makes another character. In all seriousness Personal Story should be repeatable for each character.