I think the next job is going to be aiming. A couple of ideas:

1) Gambler: Throwing dart/cards/etc + whip, has melee and ranged 'stances' used for their filler rotations and unlike RDM, it can fully decide which one they'll be at, but you can't use the ranged combo at melee range. Special attacks are all RNG 'gambler' based, but they don't define dps throughput, instead adding utility buffs/debuffs on top of the damage.

2) Artificer: Wields one-hand hexaguns loaded with magic rounds. Through combat you need to 'prep' the ammo you're going to use by mixing magic components with a system that feels like a mix of Mudras and Motifs. Thematically a mix between FFXI's Corsair and FFX-2 Gunner jobs.

Having said that, I also feel XIV could use a true nature-dweller job in the future, likely a caster that manipulates wildlife and plants with a classical RPG druid archetype, which could be dubbed as 'Shaman' for FFXIV.