I have been watching NCIX sales a lot the last few months and noticed and interesting trend. Before the release of 3xx, most of the video cards being discounted were 2xx cards, with the occasional 9xx. With the release of 3xx, the amount of 2xx cards was about the same, however, suddenly there was a flood of 9xx discounted cards, far more of them than the previous 2xx supply channel clearance.
What does it mean? Hard to say. Either the Manufacturers or Nvidia were probably trying to maintain Market Share, seems doubtful to me that 3xx Sales had enough time to take Market Share away yet. I think it means that Nvidia takes the 3xx and Fury seriously as a threat to their Market Share, but how much of an impact AMD has had on Market Share is too early to tell right now.
That said, given the small size of the $500+ Market and how Fury X sells out fast when available, I think AMD has probably made significant gains in that part of the Market. That will make them some $, but 3xx is where they really need to sell well to make good Profits and gain Market Share.