Do YOU think we'll get a new Tank and/or Healer in 4.0? And vice versa.

[Shippuu]

Tenzen, Ayame and Auron are certainly not tanks.

Auron, not a tank? Really? So ignoring the fact Auron is technically not a samurai (he is referred to as a Warrior Monk and is never classed as a samurai). He most certainly has tank elements. His story alone places him as a literal Guardian. He is very strong in the defensive department and his sphere grid grants him skills such as:

Guard: Allows character to take damage for an ally.
Sentinel: Allows character to guard allies while in defensive stance.

These skills are unique to his section of the sphere grid meaning only he can learn them initially by default. So it's funny you'd try to use him as an example of a samurai who isn't a tank when he's got some of the most obvious and very tank - like abilities.

As for Tenzen and Ayame, you'd be hard pressed to find any important characters in FFXI that would be considered tanks. I would point out Tenzen is on a mission to protect others, is considered the Guardian of Phoenix, and the origins of the name Tenzen come from the Tibetan name Tenzin which means Defender of the Faith.