Predictions for job(s) in the next expansion?

[Archwizard]

I'd rather they work on some of the existing jobs with issues.

I'll take a MCH-like MNK overhaul before another job.

Overhauls can happen during or between expansions, while people look forward to jobs that will only be released with expansions. SE makes money off advertising new jobs in the expansion, not off "existing job is better."

Coming into a thread about new jobs to discuss old ones is virtual nonsequitur, particularly when concensus by pattern is that new jobs will come anyway, and experience shows it isn't a "one or the other" deal.

And if there is a second Job it will be
either Rune Fencer/Mystic Knight or Time Mage.

I'm skeptical of Time Mage as we already have jobs available to cover the same attributes. Time Mages have never really slotted into any particular role, being equal parts support and damage, and every aspect of them is covered between AST (buffs, Regen, barriers, cosmic attacks, even its former time-bending spells) and BLM (Meteor and haste effects). I'd even go as far as to say AST is just a rename of Time Mage for 14, aside from the Gambler aspects and support specialization.
It would be like asking for Berserker while we already have Warrior, Magus while we have Black Mage, or Ranger while we have the bow-wielding Bard.

Rune Knight will likely be preserved for 7.0 for the next tank class.

I doubt Rune Knight/Fencer as the next tank, too. The job's role in 11 was to be an anti-magic tank wielding large swords, all of which describe the DRK here.

However, with DRK tanking here, seeing RUN as a DPS would complete the swap -- the question then being what weapon it would wield. RUN and its various aliases have all been classically associated with swords, while just about every sword type is covered between PLD, DRK, SAM, NIN, and RDM.
(I would say maybe Scimitars, but PLD's got a couple of those already.)

Tank: Green Mage (Uses hammer and is good at support)
DPS: Rune Fencer(opposite of Red Mage play-style; mainly melee then switches to magic combo), Viking(uses two-handed axes)

Green Mage as a tank is... certainly a confusing choice. Green Mages in Tactics have really only existed for the placement of CC effects and damage-reducing buffs. CC really doesn't have much of a place in 14's raid scene, and DR alone doesn't make a successful healer or tank. If any mage job should have been a tank I would have said Blue Mage (as the job designed to be beaten on by foes) were it not already implemented, but Green Mage is obscure and doesn't really have enough substance for even that.

Meanwhile, Viking is just Warrior as a DPS.