Don't forget that all FF games levels cap at 99 so we WILL be seeing increases in the future, and with that higher spells & new ones.

I'm thinking Water + the enfeebling spells will be given to a new class which becomes RDM.
It's already confirmed we'll be getting Tamer/Beastmaster & a Summoner type job & class in 2.0.
We'll most likely be getting Muskateer/Corsair, and CNJ/THM spells will be expanded to -ja's etc.

Also there's nothing stopping them from doing Fire II / Fira II / Firaga II etc. as we gain higher levels.