Predictions for job(s) in the next expansion?

[Archwizard]

Really, the only picks that make sense to me are Caster and Healer. It would give four actual jobs to every role except for Physical Ranged, which just got DNC.

Most likely. Even if we assume Melee are still on the table because 'it's been just as long since a new addition for them as for Casters,' they reached 4 jobs first so their "need" is lowest.

Plus the only hints towards melee jobs in the last patch were Thief (which was basically a dressed-up NIN), Beastmaster and Berserker, and unless the devs really say "PS we're going to make a new melee DPS job that's aesthetically like WAR and uses weapons like DRK's but shares MNK/SAM's armor despite it being the most populous armor class", the next melee is most likely to be a BST Limited Job to hold them over for a while.
Which I think is pretty fair -- "Five to a category but only if the fifth is Limited" -- particularly since Limited Jobs are independently balanced, and would nip complaints about an extra Caster in the bud.