I mean I doubt they are still making the R300 cores. The more time that there are both R300 and R350 cores out there the more time ATI spends competing against itself. The 9500pros will probably be faster then the 9600s (since I believe the 9600s only have 4 pipelines), and most people would probably buy 9700s over 9800s (see Ed's blurb on the front page).
I'm sure they won't run out of R300s for a while because they were reportedly getting such good yeilds, but it's in ATIs best interest to get rid of them as quickly as possible. I doubt they want to end up with a situation like the R200/8500, where they have so many extra cores around that they end up creating a "new" card - the 9100.
- JW