Okay so a lot of people were estacic about Ninja, and There are some Jobs I wnana see in game as well (Like Spellfencer and Blue mage) But I wnat to talk about a particular Job because I don't think it is actually possible to Implement it:
I'm talking about the Red mage.
First what is a Red mage: The Red Mage is a mage with access to both White and Black magic, however it usually come at the price of not getting the best spells form either, usually the final upgrades to elemental and cure spells.
Reason 1 why Red Mage won't be Implemented: Ability exclusivity.
For all the disciplines of War and Magic, all of the abilities are unique. You must level a white mage for Holy. You need to level Summoner for Enkindle, and if you wanted Raging Strikes, Archer has to be grinded. Because of this Red Mages as a class can't exist because they are sharing spells. In fact the cross-classing abilities make it redundant because...
Reason 2 why Red Mage won't be Implemented: Because it already has.
Because of Cross-class abilities certain classes can play like a black mage these Classes are the Disciplines of Magic.
First off: The Arcanist class seems to be the closest to the Red Mage, due to having attack spells and healing spells without grinding other jobs. The Twist however is that they can choose between two more specialized classes; the white scholar and the black summoner. Also note that the Arcanist needs level 15 in the related class to unlock either.
Equally close is the Thamaturge, followed by the Black mage: First off as a class, the Thamaturge guts access to a wade array of conjurer abilities, among which is Aero and Cure, making them are more genral Red Mage until you reach the 40s and unlocked Fire III, but by then you probably unlocked the Black mage Job, which locks you out of the Conjurer's skills, bur Black Mage can still pull off a little bit of red because they have access to Psysick a variant of cure that may be weaker than the normal cure, but not much else.
I say that Thamaturge is equally close to Red Mage becuase the best magic abilities are locked to the jobs. A Thamaturge does not get spells like Flare or freeze meaning that the AoE rotaion will suck, meanwhile they also cannot get the White mages ability such as Regen since Job abilities are exclusive to the Job itself and the White Mage job is an evolution of the Conjurer class.
Ironically the Conjurer is the least able to use Black and White magic because their only crossclass abilities from Thamaturge are Swiftcast and Surecast. Both are more geared to helping with their healing rather than mixing magic. White Mage also gets Blizzard II but only that as a Black attack spell.
The only way SE would even add a Red mage would be to make renamed (and likely nerfed) versions of the existing spells, and likely only as a class (since if it was a job, a specialized class by default it would cause some problems and few people would play it)
Well it appears Duelle and Ramsey have put up a plausible idea on how to implement Red Mage, so I take back that red mage cannot be implemented