Samurai, sure. Rune Fencer (Rune Knight, Mystic Knight, Spell Fencer, Spellblade), sure. Dark Knight technically can, but the Darkside/Darkness ability is ill-suited to tanking. Puppetmaster or any pet-focused tank is contrary to ARR's movement-heavy design. Remember that there are no true "tanks" in FF games of yore; you really just have to look at what has been the hard-to-kill character you dropped at the front of your party. Anyway, durable jobs in previous FF games (at least two appearances):
Already used:
-Fighter/Warrior
-Knight/Paladin
Already used as non-tanks:
-Dragoon
Other possibilities:
-Berserker
-Templar
-Viking / Pirate
-Mystic Knight / etc
-Dark Knight
-Samurai
Kinda-sorta durable-ish, largely due to nebulous concept applied broadly across games:
-Blue Mage
-Beastmaster
Only durable as super-jobs or screwups:
-Black Belt / Master Monk / Supermonk
-Ninja
Among those that are most likely, I would say of their possibility:
Templar: Ripe for the picking with Ishgard in the lore. Only possible with LNC right now, which would be a decent mechanical fit. Would be odd to have both LNC jobs coming from Ishgard, however. Any alternative would require a new class.
Berserker: Could come from PGL with some modification to PGL's ability set, or could come from an entirely new hammer-wielding class. Berserker spirit already somewhat claimed by Warrior, however.
Viking: Axe and sword tanks already taken. Really would only make sense if you created a hammer-wielding class or similar (perhaps sword-and-gun class).
Mystic Knight: Mechanically infeasible as tank with current classes. Needs a new magicked-sword or two-handed class.
Dark Knight: Technically could come from LNC, but that would be weird. I'm not fond of the idea of a Dark Knight tank in the first place as it requires cutting the Darkside ability considerably.
Samurai: Once again, could come from LNC. Would need a story to go with it, and would cause a small revolt for not using a katana. Otherwise, new katana-wielding class.
TL;DR: No really good choices right now. Templar from LNC is as close as it gets, and it has lore drawbacks. Berserker from PGL could work, but requires some serious work filling out necessary tank traits.
Uh... you have no attack spells. All you have for healing is a gimped Cure with half the magic damage stat and otherwise equal MND. It would be roughly equivalent to SMN or BLM healing.