In response to your query, I would only suggest including "Forbes.com" blog figures, beyond their current footnoted status, in the event that they can be cross-referenced with reliable hard-data and hence triple sourced as good and ethical journalistic practices would dictate. If a second source of reliable financial hard data could be found to substantiate the $8.5 billion (meaning financial data, not simply a rehashing or referencing of the Forbes.com blog post itself), then I can't see why it wouldn't be duly considered. Until then, however, the article seems fair and balanced, as is.