I'd think Dancer would more than likely be next.

It'd be awesome to see Chemist, Garlean refugee trainers of some sort so they can use Guns.

I'd really LOVE to see Oracle/Mystic/Mathematician (Onmyouji) either as a Healer or a major De/buffer/DPS.

Lastly my idea would be Astrologer ---> Time Mage; "Time Shift" "Reverse Time" = Cure Spells "Relativity" = Medica though it'd be fun to use "Time Loop" Regen dependent and burst heal with an active "Accelerate". There's just SO much room you can play with time and physics.