Could this expansion be "Give The People What They Want"...
The following is total speculation on my part and should definitely not be taken seriously at all, In the slightest...
By this I don't mean Blizzard has changed any of their plans (which were probably laid down months if not years in advance) but I do have to wonder if the 'release' of the Pandaria title, dropped in exactly the same way as the title Cataclysm was discovered, isn't partly a reaction to last quarters 300,000 subscriber drop. This on the back of previous 600,000 subscriber drop, is 900,000 subscribers lost in 6 months, half a year and nearly 1 million people have quit WoW.
Now before you start, or before I start, this isn't a rant about the death of WoW... Cataclysm was good, it was goooood, people are dropping away for a tonn of reasons, new MMOs/New content done with/It's summer go outside in the sunshine (yeah I know!)... but.... what ever the reasons, Blizzard will have noticed. Is it possible that the internal board meeting went:
"So you're losing nearly a million users in half a year... we need a seriously popular new thing to pull those numbers back, we're up against Rift and Star Wars, they're giving people lightsabers.... people love lightsabers! What do people want, what is the whole player base crying out for?"
"Don't be ridiculous you how are you going to build a whole new story based on dances and moose?"
"well everything else in development is bread and butter Azeroth stuff... we..."
"Well, there's always the Panders, people liked the pandas... right?"
"no wait... go back, tell me about the panda people again"
Lo and behold, The planned '1,000 islands' expansion gets a new island added, Pandaria, and Blizzard needs a way of making damn sure people know about it without making anything official. So, knowing that people were watching last time, rather than find a private way to trademark their stuff they do it the exact same way Cataclysm leaked and sit back to see what people make of the idea.
If the backlash is harsh they can turn around and say "don't worry this was always just an experiment and we're not doing it the new expansion is actually "BC2: Crusade Harder"
If the reaction is "ZOMG they gave us drunken monk pandas?! Squeeeeee!" then hey, jobs done.
Reaction has been predictably mixed, with any luck the next expansion will be too, lots of little stories branching off in the aftermath of the Cataclysm... but... if someone up there is thinking this could be WoW's make-or-break expansion, who knows, maybe down in the caverns of Undercity we'll find the Goblin Dance Studio-a-tron 9000, and stepping ashore on the lost nation of Kul Tiras we find they all ride around on Mooses.