I wonder if Ultima having interactions with the Ancients gives any further meaning to the Convocation seat names being named after the Scions of Light from FFXII (the light variants of the Esper summons), the fact that their symbols are made of parts of the Esper summoning glyphs, the use of Zodiac symbols on their memory crystals, and the presence of the Seat of Altima.

At first it could've been put down as simple fanservice but the writers' use of Ultima in Pandaemonium could open up a whole can of worms. Or it could mean nothing more than the writers just trying to tie loose ends and they'll never come back to the Ancients again.