I hope they actually change summoners around a bit and give them more of an important role in the party.
Such as

Titan=Paladin
Carbuncle=white mage
Ifrit,Shiva,Ramuh,Leviathan=black mage
Garuda=Red mage

So lets a party needs a role filled and they see a summoner is seeking they could ask the summoner if they would be willing to feel that role.

And i would love to see avatars like Odin and Alexander be more of a relic weapon.

Say Odin=Dark Knight with Apocalypse and Alexander=Paladin with Excalibur of course these two would be just as hard to get as a relic weapon.