Honestly I'd much rather have Paladin fixed before adding a 3rd Tank Job, something akin to what it was in 1.23...right now it's merely a Knight from FFT without the weapon/armor/etc break. At least Warrior has more to do than pressing 123, it's more engaging rotating enmity combo, keeping Maim buff up and storm's path/eye on the mob while also timing an Inner Beast for a hard hit or simply Steel Cyclone for hate/damage. When players see Paladin they think of a knight in shining armor with healing abilities, subpar healing abilities but nevertheless healing abilities (Cure in this game is beyond subpar) and 1.23 Paladin was that. 2.0 is not.

As for adding a 3rd "unique" Tank into the game that already has a Defensive (Paladin) and HP (Warrior) sponges, what could be added into the shallow battle/stat system that we have. People speak of Evasion tanks ala Ninja from FFXI but Evasion isn't a stat in FFXIV 2.0. For it to 'tank' it would need to evade but if it's able to evade attacks that do 50% (for example) of a Warrior's HP then that becomes broken. Then if it's not guaranteed to evade, it would be hit for massive amounts of damage and be "useless." It just won't work in the current system and is either too broken or too useless. Right now all a Tank can do is have damage mitigation (traits/parry/shield block) and or Vit (HP) to absorb hits. So when looking for a a new Tank it's one or the other (even though it's a bit of both).