When I think about it I'm am starting to think Dragons are associated with Zodiark.

1. Dragons live a long time. Midgardsomr lived through multiple astral/umbral eras.
2. Ultima Weapon looks like a mechanized dragon. Sabik is a star in the "serpent" constellation. Midgardsomr is the "world serpent". Zodiark is referred to as a serpent and looks like one in FF12. Dragons are also referred to a serpents.

According to lore it was the infighting of Man that caused the 1st umbral era.

It also appears (if you read heavensward lyrics) that Dragons are fed up with Mans broken promises and now wanna destroy eorzea. A lot is pointing towards Ishgard since elves where 1st to migrate to Eorzea. Gridania is roughly 500yr old, but Ishgard is at least 1000yrs.

There's also the prophecy saying that the 7th umbral/astral era is the last one and that a shadow (Zodiark? Especially if you see his summon on FF12) will rise