After the green fire class quest for Warlock, Blizzard will make equivalent for other class (but not quickly).
If green fire and a epic quest in Black Temple look good for Warlock.
Some class are easy for this. Drood can obtain some epic Form after a quest in the Emerald dream. Paladin can do something with the rest of the scourge in Ice crown.
But what will it be for mage ?
An Epic quest in Nexus and the possibility to take the form of a blue dragon. Oops, it's already taken ...
Some work for the Kirin-Tor in Dalaran ? But it will be an Epic escape from violet hold for Horde mage ...
My idea would be for something involving Karazan and Medivh.
But I really have no idea for some symbolic reward, like the fel fire for warlock.
Time for good idea !!!