Blizzard should just throw out a Warcraft 4 and have it cover the storylines WoW has up to Wrath. Would be a good way to keep the story in a game form as well as great for those that missed it and Cataclysm is the only WoW they know (not many I know).
Plus...it'd be good to have a new Warcraft RTS game, no?
There aren't that many new players that didn't experience pre Wrath. I wouldn't buy a game that I already played a different way. A movie of some kind I would watch, but not a game with the same story. I don't see Warcraft 4 coming until after Wow is done unless it takes place in the past.