Tanking in Wrath of the Lich King
We *will* give you the tools to do it. We just might not give you those tools the same way another class gets them. There are no two-handed tanking weapons, yet I suspect 50% or more of DKs will use two-handed weapons. Neither DKs nor druids have shields. Druids need defense less than other tanks because they can achieve crit immunity. We can do something similar for your damage reduction (bake it into bear form, or put it in a talent are two obvious choices). Now, when you get your leather though, we are assuming you gem and enchant it as a tank would.
I'm sorry we are neglecting paladins on the forums. None of the tanking trees are very far along yet, and ironically the DK ones are probably the most stable. The paladin ones may be the least stable since the class changed so much, so it's hard to offer a lot of comment on specific talents right now. I mention druids a lot because we are talking a lot about them right now. The Arms and Fury warriors recently got some really nice work done on them, so hopefully Prot will follow. (But again I stress we won't know if the talent trees offer all of the threat, mitigation, survivability and tools they need to until we compare endgame tanking more.)
As far as what the Prot warrior brings to a raid, it is true that all tanks bring some ammount of target debuffing. But more importantly, we are in the middle of a pretty big analysis of raid buffs and debuffs. It is a large enough topic that we probably shouldn't muddle up this thread too much of that discussion, but in brief:
The overall goal is that you should want to bring raiders because they are your friends or because they are very good players, not because their buff is so awesome that you can't live without it. We would like you to be able to get all of the big buffs and still have some remaining slots that you can fill how you want (you know assuming you have enough healers and CC or whatever). We would like to get things to where no single spec always justifies a raid spot because their buff is impossible to replace or live without.
Tanking in Wrath of the Lich King and Itemization
No class should need an awesome set of tank gear for a L76 dungeon. Once you get close to 80 and start to talk about heroics, then you absolutely need some good blue tanking gear, and that kind of stuff is available as drops and quest rewards.
Our early tests suggest DK mitigation, avoidance and health aren't far below other tanks (assuming those tanks are using similar gear and aren't coming in with Sunwell epics). Their avoidance tends to be a little higher and stamina a little lower, but not significantly (and I should stress that these are very preliminary tests). It could be that the mobs just hit too hard.
One change we made recently is baking in the old bonus from Blessing of Salvation into tanking forms. Up until now you were pretty much just doing without the old Salv because there was no way to replace it, and many raiding guilds will tell you that buff is (was) mandatory. Now you get it for free.
That obviously won't help survival much, but it will affect threat enormously.
Feral Tanking and Itemization
I totally get this. Druids won't be popular tanks if everyone knows them as the OOM tank. When I say "big health pool" I'm not talking about 30% more than a warrior, and I'm not even sure that's the route we'll go. But since the "big health" idea generates a lot of discussion, I'll walk you through our thought process.
Druids are going to have a harder time hitting the armor cap in Lich King largely because there is no leather tanking gear, and virtually no bonus armor at all (except on a few pieces like rings and necks). Now we can't just make druids do without armor, or they won't compete with other tanks. We can't just bake the armor into Dire Bear Form though, or we risk making resto druids even better in PvP. So when I have mentioned big health pools, that is partially because we're trying to solve the problem where druids need armor but can't get it. Big health is a way to do with less armor, but it's not a total fix for the situation, it definitely has drawbacks, and it doesn't mean 30% more health and 30% less armor. If I had to guess, all of the tanks will end up having pretty similar endgame stats, minus obvious things like block.
Keep in mind how good a well-geared druid tank would be in live if we hadn't added Sunwell Radiance. It is surprisingly easy to make bears too good or not good enough. We have to tread carefully.
But we haven't changed the design of wanting bears to be able to MT. And that doesn't mean technically they can MT but all the healers complain and as soon as the warrior logs on, you eagerly swap him back in. MT means MT.