I would much rather see a kind of "Gun Mage" from FFX-2 than a Blue Mage and I'll tell you why.

In FFX-2, Gun Mages had access to Blue Magic, but they also had access to a variety of other skills, namely with exploiting weaknesses in enemies. If we could get a bunch of Blue Magic to be learned through Job Quests and otherwise have weaponskills for everything else (kind of like how Rogue/Ninja is set up), that could work really well here.