Fr'instance, when WoW released, Mike Morhaime says that every available employee was working on it. And production on Burning Crusade started about six months after that, when Blizzard determined that WoW was "stable." Other interesting tidbits (specifically from the recent WWI) include the fact that China is WoW's biggest market (people there pay by the hour, not by the month), and that Blizzard expects WoW to last them at least 10 years. So we may still be grinding murlocs in 2014.
It's also interesting that Blizzard says they don't plan budget limits for games-- either they're going to make a good game, or they don't bother making the game at all. Most companies probably wouldn't have ditched Starcraft: Ghost so late in the process, but Blizzard seems totally and completely committed to releasing a great game or not releasing a game at all. Interesting tactic, but then again it's worked for them so far.
[ via WorldofWar.net ]