We have all gotten a head start in learning to use out new abilities. Some classes are more or less the same. Warrior tanking has become a brand new ballgame. Prot Warriors used to put out 200 dps in their tanking gear. Now they are putting out 450 plus. Threat is thru the roof. People are AOEing entire instances. The time will soon come to once again seperate the good tanks from the bad ones.
We will be running new instances, with new mobs, with new abilities. We will probably be able to blast thru the first few with little to no effort. Once we start getting to 75 plus and replacing our gear, things are probably going to get a lot tougher.
We will be asking for players to use CC again. We will be selective on who we take on runs. What kind of utility does that class bring? If you are currently a tank and just AOE tanking everything, YOU ARE NOT PREPARED.....wait that was the last expansion.
My advice if you plan on running some 5 mans or 10 mans before Wrath is to practice running things how we are going to run them in the new future. Out CC has most likely gotten incredibly rusty. Mages aren't sheeping, Hunters aren't trapping, Rogues aren't sapping. I have and idea that this could lead to a lot of annoying wipes in the very near future. It will all even out after a bit, but starting now will make the transition that much easier.
All tanks should be able to multi-mob tank when needed, but it is also the responsibiliy of the CC to make sure that their targets stay CCed. A dead healer can't heal anyone.