[willfulwizard]

Giving out that sort of information would change some amount of people from just buying now to waiting for the new product. That's nice from a customer standpoint but bad for Apple.

Consider:

1) Less outdated inventory moved.

2) More problems keeping up with new product demand, which Apple already can't do.

3) More customers think about the question of buy now or wait when making a purchase. This doesn't sound like a lot, but Apple strives for the simplest possible buying experience.

[dasil003]

Don't forget:

4) The freedom to release or not release anything at any time.

[jsprinkles]

Good points. I hadn't thought about it from a supply chain perspective or that of cannibalizing sales. That's definitely a consideration.