Give a suggestion of new class on game.

Doma! Ok so more likely Near East will be next in the line for content, but can hope, heh. Anyway...
Samurai, kinda expect to be coming already though still curious if its tank or dps.
And then, while not quite final fantasy but still a Square Enix thing, the Bravely Series has a couple classes that would work for Doma, Exorcist maybe Kitsune (Though would need to be a lot different then the Bravely one), those would be pretty neat and something new to have.
Exorcist, would be something of a support class and debuff class either as a healer or possibly dps support like bard or mechanist since they somewhat manipulate MP.
Kitsune, I guess it could get worked in as a dps class, and no you wouldnt really need to have a specific race for such, it could just be something like having the character invoke the spirit of a kitsune.

I'd love to see Thief get a proper job in the game but it's probably not gonna happen considering how they were even afraid to call the "Rogues" Thief's.

I'm going to be very straight forward....

A Gunblade user.

Currently the 2015 anniversary hinted in...

Red Mage

Samurai

and one of them is going to be a Tank job and the other a DPS Job in 4.0.

Tactic's Ogre: Swordsman - Evasion tank and counterstrike mechanic for damage.
Vagrant Story: Riskbreaker - Melee AND Ranged DPS, Sword n Crossbow. Range varies with diferent stances, builds up Risk for higher crit and crit damage chance in trade of accuracy, defense and healing.
Final Fantasy Tactics: Oracle - Healer/Debuffer. Lowest healing per minute of the bunch, but tons of debuffing and buffing skills for a class that offers several status effects and battle control.

we need..................................


DANCER/SONGSTRESS

Would work as a healer buffer and mob Debuff support class with a agro taunt attack eyes on me all mobs in range turn and look at dancer and get pacified.

The ones I'd like to see from playing tactics are Geomancer, Illusionist and Arithmetician

I am definitly all for the mystic knights. Sounds much like a shaman in WoW however in tank form. I would grind to level cap on day of release if this gets added

Musketeer: A Job that wields guns. There have been several NPCs (particularly pirates, most notably Merlwyb and Rostnsthal) It could be the Corsair of this game, without the buffs of course, since Astrologian (which by the way, is the Time Mage in this game) has cards already and we don't want another Machinist. Might as well give Musketeer two guns too since Merlwyb also uses two, and do some pretty nice flips like Laura Croft in those ancient Tomb Raider games (jk).

Ranger: A Job that branches from Archer. It's a Job that's more focused on damage-dealing rather than being a support like Bard is. We could throw away the concept of Wanderer's Minuet to them too, and remove it from Bard I suppose.

Mystic Knight: A melee DPS or tank that enchants their sword with magic, with different elements giving a different effect (since they removed the element wheel). Fire increases damage, Ice increases MP, Water absorbs HP, Lightning adds a DoT and debuff effect on enemies (?), Earth increases defenses, Wind increases speed, evasion and movement.
People have ideas of merging Mystic Knight and Red Mage and i'm absolutely against that idea.
Initially, I had an idea of Dancer and Mystic Knight merging, but I'll make them separate here.
They can use scimitars.

For the hinted Jobs:
Dancer: It's a popular opinion or conclusion that they'll be a healer, but I honestly want them to be a support DPS (or just a support if ever that role ever happens). Dance skills that buff the party with the cost of not being able to do anything else other than deactivating it or if it gets interrupted, or skills that are dance steps that you press in a specific order, somewhat like NIN's mudras, to give buffs. I'd say they could use dual blades to dance with.

Red Mage: Something challenging to implement with the limited Tank/Healer/DPS only roles. Only thing I could say is they could look at Scholar, which has respectable DPS for a healer since it branches from Arcanist, and try to work around that idea on Red Mage.
Another thing is being a melee and a caster at the same time. Well, just give them stances?
Uses rapiers.

Samurai: It's going to be a DPS, I'm pretty sure. If it becomes a tank then it could focus more on evasion-tanking. Uses a katana.

Blue Mage: I'm really thinking it should be a tank because of the concept. FFT and FFXI's image of Blue Mage aside, it looks like a masked hero/knight with a cape, Sooo it fits being a tank.
Not to mention learning monster abilities by mostly getting hit by them and defeating them, they could revolve somewhat around countering attacks. They can also learn monster skills from Job quests involving defeating monsters.
They could probably use only swords, share with GLA, and keep the PLD-only swords to PLD only.

For Existing Jobs:

Machinist could've just used gunblades, since it's inspired from Garlean or Ironworks technology I believe? Not really sure but they had such a good opportunity to give a gunblade job but overlooked. I won't see a job that uses a gunblade anytime soon.

Summoner could use more summons that still follow the three roles, but have unique skills. Shiva and Bismarck can be a tank, Ravana and Leviathan can be the melee DPS, and Ramuh can be the ranged DPS. Also make the tank pets useful in encounters rather than being only useful in solo-ing.

Scholar can have a Phoenix pet, I suppose.

Berserker 2h dps and can use 2h axe/sword/hammer

A Beast Tamer/ Beast Master. A whip as his main weapon. Melee dps with a short range like DRG. He can summon beasts he tames like SMN but they make physical dmg instead o magical. Basically a physical summoner. It fits really well in the realm of Erozea and Lore and I really wonder why its not a thing yet. Who you thought tamed all the beats we ride as mounts. Its their guild masters that does this work.