If they do add it, though not likely since a healer is probably next, I still feel it makes no sense. It's literally just a gun, with a blade under the barrel for 99% of of their arsenal. Plus the weapon isn't to just a standard gun and blade. There's the Heirsbane(Just a fancy looking stock Garlean Gunblade), Bradamante(Halberd style Gunblade), Hammer Variant, Gauntlet/Fists Variant. Shield Gunblades... Think that covers most of it?

Either way, in the end they are just guns built into the weapons, nothing magitek involved in them, the magitek coming from other sources like the suits for the baddies that could do no more then just pew pew and slash with their weapon.

That's why I think their would be little to base a whole new job off of it. Nothing unique or special about the weapon, the effects and powers coming from the persons wielding them instead.