I liked the Arabic feel of ffxis blue and I'd kinda like to see that feel return. I think the blue mages should make a return as the high guard of the Ul'dah Sultin. Like a secret police.

Now lore is not all that interests me because I am a blue Mage freak, and love everything about the current armory and job system coexisten
Blue Mage should make a return basing A). Either basing in the new pet class and using a whip as a main weapon, reminiscent of Quistis. The pet class should only have good petcontrol (full control is the purpose of a beastmaster.
Now, a monsterfarm is going to be needed for this next idea.. Capturing monsters allows you to get items from the monster regularly, like gathering (oh perfect for a shepherd). When you have a monster as a blue Mage, it allows you to call upon certain skills from the monsters, I'd say up to 3 until the increase the level cap. The blue Mage will have two other skills. A "Combo Affinity" Skill that makes your next blue magic usable in a weaponskill combo for increased effects, and your 15 minute which will be a weaponskill that I'm not sure the effect should be, I've had a couple ideas but I never thought out this build like this before, though I like the name Azure Oblivion, it's a kind of play on the fact that blue mages learn, but oblivion meaning forget. Probably should inflict amnesia or something to actually lock out an ememies skills. (lol im just writing as I go now but sounds so epic)

But yeah I'll post more but I'm on my iPod...