Next Tank Job?

[Gamemako]

I'd LOVE if we had a caster tank like Red or Blue Mage...

Blue Mage could be a tank depending on how it's implemented, but Mystic Knight makes the most sense for a magic-oriented tank. You already have sword, armor, and spells for use at close range.

If SE ever adds Ninja, I think they should make them an evasion tank like in FFXI

Both unlikely. Ninjas were never supposed to be tanks; they ended up that way due to gimpy balance and were only eventually given enmity boosts because of how the players had adopted the job. Evasion tanks also don't work in ARR, which relies heavily on spikes to pressure tanks.