The Question is how will tanking be in ESO.
from one of the AUA's:
[*]You won’t need to get every enemy’s attention. Every player can take a few hits from standard attacks, and they have lots of ways to take care of themselves. Many healing abilities affect an area, so your healer (if you only have one) should be able to take care of several party members.
[*]In a fight with a large group of enemies, a tank’s ability to control the fight is critical. Stun the healers, interrupt the spellcasters—you’re the best party member for the job, because your stuns and interrupts will tend to get those enemies to attack you back.
[*]You do need to stay engaged with tougher monsters, like bosses. They hit much harder, and your damage mitigation and extra health will keep you alive where other characters might die.
In ESO you will have just 1 aggro ability (1h/Shield) which taunts a mob, that skill will be very important for boss fights so that a DPS especially a melee DPS doesn't get aggro.
In order to get to a boss you will have to fight your way through lots of mobs. Therefore a Tank will need lots of CC abilities, AOE skills and enough damage to keep them attacking him.
This means that a Tank might need two sets of gear. 1 for dmg and 1 for boss tanking.
The question for me is how much damage will a tank be able to do while he is still able to tank every Boss?