The various choices blizzard would have are usually close to too close to the actual classes that are already available.

Acolytes, Disciples, Monks, and other Holy Warriors are too close to Priests, Spriests and Paladins.

Archdruids, Dreamwalkers, Plagueshifters, etc, are too close to Druids and their kind of "disease removing skills/nature preservers/tree hugging skills"

Shadowhunter, Witch Doctor and the likes, are a lot like Shaman. Granted, Shadow Hunters use a different kind of way to obtain power.

Medics and Tinkers are basically Engineers, not a whole new class. the skill the goblin in Area52 used to revive another goblin was clearly an Engineered weapon, and so pointless to make a new class for.

The only healing classes that I see that COULD be implemented (not saying they have to, I thinkt hat if they revamp the current healing mechanic, enough people would regain interest in rolling a healer), are either a:

- Shadow Hunter (They are masters of voodoo magics who can use their spirit-powers to both heal their allies and place curses upon their hapless enemies. The Shadow Hunters walk the line between darkness and light in hopes of salvaging the future for their savage brethren), which kind of reminds me of a hybrid between a resto-shaman and a warlock, and could be used by the horde

- Runemaster, which would use kind of the same mechanic as the Death Knight when it comes to skills.