As I just finished my last 80 (dragoon) their 5.0 job story drops the idea that all of the 7 dragon brood (Midgardsormr's kids) are responsible for the stewardship of the star in his absence.

I'm thinking the remaining brood will come back into the story if we are on the verge of a calamity that will allow Zodiark out of his moon cage. This may also be the Heavensward hint that Yoshi-P referenced.