Whatever the final number is you should multiply that by a 2 to 6, to account for the people that are in DDI and not on those boards… thus whatever the number is it is nearly 100% irrelevant other than to represent a bare minimum number.
Something else I think people really need to understand is D&D is not expected to be a huge money maker. As long as it is making some money and growing, even if slightly, it will be considered a success. As long as they can get revenue from the license in books, movies and video games it will be doing well.
Also the dependability of the income is going to be a great windfall for them. It might even be the most important part. It will allow them to make long range plans like they have never been able before.