As far as my thoughts on the topic in general... I think people crying about not wanting tanking homogenized aren't looking at things quite right. In the end, it doesn't matter if all tanks have the same effective health, mitigation, avoidance, TPS, or whatever other stat. What matters is how each tank goes about getting the job done.
As long as Paladins are still popping Holy Shield whenever it comes up, and Death Knights have cooldowns (albeit weaker than they are today) to rotate, and Warriors and Druids are primarily concerned with threat output with a few cooldowns in reserve for when things really go bad, then the current flavor of tanks has not really changed at all. We are not truly the same if we arrive at the same place via different means.
I don't see anyone complaining that Blizzard wants all of the pure DPS classes to do essentially the same DPS, assuming equal gear and skill, unless their argument is that for whatever reason, they feel they should be just plain better than another class. Even if a Hunter and Mage do the exact same DPS, nobody is going to argue that, "Oh noes, ranged classes have been homogenized, it's all the same now!!" The fact still remains that Hunters and Mages achieve that DPS in a fundamentally different way.
Such will be the case with tanks, too. Until our actual abilities become copies of each other, our various stats play no role in the homogenization that everyone seems to fear so much.