Call me an elitist tool but I'm praying they make cataclysm so hard that even raid geared stacked 5 mans have trouble completing the hardest heroics. Then add hardmodes to them on top of that. Then add RNG back to the game in ways that make you yell "Come get some" and light up a cigar every time you down a heroic boss. Then convert all normal gear to the emblem system and make it rare item quality save epic drops only for final instance bosses and hard modes and bring some pride back to this loot pinata of a game

Hell I'd be ok with Deathwing making random appearences throughout heriocs thrown flaming balls of death at anyone that hasn't moved in 10 seconds similar to BAAL attacking randomly in the worldstone keep in diablo 2 if you stood still for too long. Bring on the pain!