This disucssion will contain some spoilers.

So simple question...

If SE release 1 new Job in 3.X era what do you think it will be?

I have no clue myself but my best guess would be something that can fit into Ala Mhigo lore or Garlean lore or at least something that allows the Job to be introduce within 3.X era MSQ without it feeling out of place either being...

Dancer Job (A lot of refugees are heading into Eorzea as was mentioned throughout the storyline so maybe a group may bring with them the Dancer Job arts or is already some where in Ul'dah)

Gunblade Job (The game been beating us with this Weapon since 1.0 and still continues to torture us with Gunblade users in 3.0 keeping this one Weapon type out of reach for Players or gameplay. Garlean Empire is rising once again and there remains the possibility of garlean defectors in Eorzea who may bring with them the Gunblade arts.)