According to post #15 from this thread, White Wolf is moving towards a PDF model of product release and away from print copies. This model allows them to release products faster and cheaper to their customers. The downside, of course, is that you'll see less and less print product on the shelves of your friendly local game store. I know of at least two that are clearing out WW product from their shelves because they won't be able to get any of the new release in and WW hasn't set up any programs yet to allow PDF sales at the retail level.
From the consumer point of view, the PDF market is still relatively small compared to the print market and caters mostly to those people who are already fans of the game system. It doesn't create new fans, which creates a downward spiral of the game system. What typically happens is that current players of a game bring in new blood, so to speak, replacing older players when they drop out. New players typically get intersted through seeing a physical copy of the game in someone's possession and getting involved that way. PDFs don't allow that physical presence, cutting down on the number of new players in the game. It will be interesting to see how the World of Darkness is doing in a couple of years.