The Death Knight in Wrath of the Lich King was the first class introduced to WoW, and it's inclusion in the game has had mixed reviews. Most folks agree that the class provided a great new element to play in the game, however its balance in raids and PvP is something that is constantly under the microscope. Ghostcrawler has mentioned numerous times that the Death Knight has taken up more time to balance in Wrath than any other class. This is problematic for numerous reasons, but has been able to be handled nicely by the designers and programmers (I'm sure there'll be some who disagree, however show some restraint in your disagreement).
So now for the hypothetical part -- if Blizzard were to introduce a new class in Cataclysm, I would suspect that it would be the healing counterpart to the Death Knight. Mechanics of the class would probably operate similar to the Death Knight's rune system: each small heal or heal over time would be castable based on an available rune, which would in turn generate runic power for larger heals. The class would rely less on spam type heals (such as the Paladin, to some extent), and more on preventative heals (such as the Druid, to some extent).
Because I'm narcissistic, I'd name the class Adam Knight. Or failing that, Arch Cleric. Of course the sadistic side of me could come into play and say "lets name the class the Monk, just to rub it in the face of all those D3 players." Again, sadistic side that'd never see the light of day, never.
The lore behind the Arch Cleric would be that the Cataclysm which struck Azeroth awakened a secretive order of priests whom had been studying under the watchful guise of a master Death Knight which converted to the priestly way of life. Now that the world is in ruins, this order of Arch Clerics called the Divine March leads the fight to restore and heal the peoples of Azeroth; seeing to the ultimate destruction of Deathwing.
So let's hear your ideas. If Blizzard were to introduce a new class to the game in Cataclysm, which we know they won't, what would it be?
Dear Chris Metzen,