I hope NIN and SAM aren't tanks.

I want Ninja a hybrid physical/magic melee dps.
I want Samurai as a dot/bleed based melee dps(they'd have to increase enemy debuff limit though) -or- a straight forward melee dps that uses a new mechanic.

I hope the next tank branches off LNC, make it the Templar and uses 1h spear and shield, release it with the Ishgard expansion, and make the back story involve the holy see. Makes tons of sense.