Blizzard knows that getting new players into the game is key to its long-term survival; they've made tons of changes to the early game to keep new players interested and make it easier for them to get into the game. There is absolutely no way they aren't going to continue to do this with Cataclysm - in fact, I kind of see Cataclysm as one big "lets get people to try the game again, or for the first time" as the overarching goal.

So here are my predictions:

- Existing players will have to buy Cataclysm in order to play Goblins, Worgen, or level up to 85.
- People with vanilla will get the revamped Azeroth, but not be able to be Goblins, Worgen, or level to 85.
- New players can either buy Cataclysm, which will let them play Goblins, Worgen, and level to 85 BUT
- If people who bought Cata but not TBC&WotLK want to play draeni, blood elves and death knights, they'll have to buy those expansions or maybe the Blizzard store will sell the ability to play those races/class.

I think they're going to change the way the game and getting new content is gonna happen. I think they've been testing out that micro-transaction stuff a lot, and I think we'll see things like "Oh, hey, next month on the store we're gonna be selling, for $25, the ability to play as a Pandaren." "We added a new heroic class, and for $25, you can play as them". Then when they do actual new areas, they can sell those individually, too. "$10 to unlock this new zone" and so on.

I think this would have the potential for a LOT more revenue for them. If they come out with an expansion every 2 years that sells for $50, that's not bad. But if they come out with a new race every year for $25, a new class every other year for $25, a new zone every 6 months for $10 - they wind up having a much more dynamic game that is always giving players something new AND they win up charging more for it AND their content development team can focus on making the new stuff as good as possible.

Just something I feel in my bones. If Blizzard doesn't do it I'll be surprised, but SOMEBODY is going to take this approach to MMO expansions, that I'm sure of. Blizzard just has the fanbase to pull it off.