I think that blizzard should change the static class system to become a skyrim like system, where your choice decides what your character is going to be. While the choice is merely based on investing points in talent trees of different classes.
You know, as like in the newest video, where Anduin choses to go paladin instead of priest. So imagine you had a "crusader" and a "holy" tree, and you just would put more points into crusader while still being partly holy.
If that would be a possible hell of a balance? Yes, probably. But balance is not working in a MMORPG no matter what talent system we have so at the end you always have perfect imabalance with some specs dominating. The new solution just would allow you as many choices as possibe, by chosing talents out of 34 possible talent trees and skills you are able to find anywhere in the world. The class teachers would become viable again, as you had to do quest chains for them to acquire new skills. As like a character who wants to use a bow, and goes to the hunter trainer to get a bow skill quest.
What do you think?