I am sure many have seen
http://www.joystiq.com/2007/08/07/rumor-target-done-with-xbox-360-core-model/
and
http://www.joystiq.com/2007/07/30/best-buy-done-with-xbox-360-core-model/
But not sure if anyone notice that Ebgames/Gamespot seems to be also getting rid of their core 360's. Check out the link below and just put in your zipcode and set to 200 miles and see whats available.
http://www.gamestop.com/product.asp?product%5Fid=020259
For my area most are sold out and do no expect to get new ones. Some do have some but again do not expect to get new ones. There where some that where sold out and where expecting some more but doesn't even come close to the premium listed below
http://www.gamestop.com/product.asp?product%5Fid=020253
For the premium the only time that they did not want more was because they had 4+ but other than that it was sold out or some had some but ALL had more on the way.
Obviously this is just an observation which I stumble on while checking to see how well the 360 was selling after price drop. Would be interesting to see how much the above changes lets say at the start of septempber or even a few weeks from now. My honest opinion is the core is on the way out as it is not worth supporting that version not just for retailers but for Microsoft as well. If anything the Core might still be available but in very limited quantities though I heard it counts for 20% of 360's sold I would say it would drop down to 5-10%. Just my guess.