My list of changes that are need.
Cooldown bursting- fix this for a few select classes mainly warriors. If you can nerf their huge insane burst down a little bit and leave all their stun/silences they will still be in a good slot.
CC's- Slap a few more shared DR's between CC's and adjust fear etc.
Healing- With burst taking a heavy nerf and cc's getting reduced you can then proceed to adjust healing.
Overall though I do believe Blizzard has got the concept and setup of a wonderful design for once to be able to adjust these issues. Why they havent yet is beyond me though. All classes will be in a much better standing if they town down cooldown stacking burst and the overall raw power of cooldowns to begin with and increase sustain pressure where landing a more limited CC chain can still net kills.
Classes themselves are NOT the problem! I think this is the first expansion where classes overall seem to be in great standing it's just overshown on what some can do (ie Disc priests/ Rogues etc) by the classes that are able to insta-gib at the moment.
Edit: Some "small" changes I think that would go along way for adjusting classes without "breaking them entirely" I'll list below
Mages- Glyph of fire blast nerf would go a long way here imo...
Warriors- Reduce the ability to pop ALL their cooldowns at once and the blanket silence on pummel/heroic throw.
Hunters- Lynx rush adjustment and BW unable to be instant reset. Increase sustain for this class in return
Resto druids- Scale back their mastery by a tad.
CC's- put all magic effects on a shared DR and physical CC on a shared DR.
Roots/Horror/Blanket Silences (leave silences when interrupting a certain school in effect, just a small nerf to the blanket silences)
I believe this will change a big part of the game and allow us to see more or less what *tweaks* can be made and other adjustments when these very easy adjustments have been added.
Now proceed to flame me like I know 99.9% of the people crying "NERF TO THE GROUND" will = \