they have broken out before how much money the cash shop makes, especially during their charity "drives" (100% of proceeds go towards the asian storm etc) and the numbers are lower than what you might think. Yes, the cash shop is a nice little money hat but its closer to $20m/month or so, which about lines up with f2p games as well. swtor for example made $170m TOTAL ($15m/mo) last year from their cash shop, and thats a game that heavily focuses on their cash shop.
yeah we really don't know exactly how much money is made where, someone who is REALLY into it can figure it out based on digging through reports and stuff. Companies also do an accounting "trick", when you pre-order something the money is not booked right away but instead it is held in accounting reserves and used to pad revenue down the road ("deferred income"). So for example if I pre-order WoD now, Blizzard will NOT count the $60 as revenue this quarter or month, but instead wait until WoD actually ships and stuff it into that quarter, or even sometimes months or years later. Companies like Microsoft, IBM and Apple are famous for having BILLIONS in deferred revenues that can be used to massage bad quarters.
I'm sure Blizzard does something similar but end of the day the number is still $200-300m/quarter from World of Warcraft (online sub fees only not one time box sales), however you wanna fudge that around thats still between 3-4m paying US/EU subs depending on how well you think the cash shop is doing. That still makes it the biggest sub MMO around, by an order of magnitude. And that number hasn't changed much in years.
Its also pathetically bad that Blizzard makes over $300m a year in profit from wow, and its going to be over a year in between content patches AGAIN. But also explains why so many companies chase the Blizzard MMO model, if you could copy it you will make more money than every other video game studio, combined. I think most have figured out it was a fluke of timing and luck, not likely to repeat any time soon, but you still get your TESOs and Wildstars.