Here's another post re Blizzcon,expansions, what's coming. This time posted at IGN, so there's a good chance it could be correct, or at least some of it is...

• That expansion pack is called World of Warcraft: Into the Maelstrom
  
  
• The Maelstrom area of Azeroth will be opened up for play. Will consist of various islands and Undermine will have a new neutral city.
  
  
• The islands will include questing zones, raid dungeons, that city, and a new arena.
  
  
• The level cap is being raised to 80 with the expansion but there will be no new talents.
  
  
• Advancement after level 70 will be through Hero Classes rather than talents. Hero classes will function as subclasses and each existing class will have 3 of these hero classes to choose from. These hero classes will not be limited by talent choices. Players will be able to choose these new subclasses at trainers when ItM goes live.
  
  
• Currently the Priest and Druid hero classes are complete and the Warrior and Mage are close to completion.
  
  
• Hero classes will be demonstrated at BlizzCon