What are some of the different theories as to how many expansions will be released of World of Warcraft

One of the most commonly used theories is that Blizzard would want to create the final expansion with the idea of characters leveling to level 100. Currently, the maximum is level 80.
For the Cataclysm expansion, the level cap is extended by 5 levels instead of 10, leading people to believe that Blizzard does not want to rush to level 100. Assuming every expansion would add another 5 levels from now on, that would lead to 3 expansions after Cataclysm.
Should Blizzard decide to add 10 levels again, the next expansions would lead to level 95 and 100, for 2 more expansions total.