The frequency of "Leaks" has me thinking that a part of this must involve Apple. There's simply too many, and Apple is too powerful, especially over their suppliers to allow this to continue.
As I see it there are a few possibilities.
1) Apple is orchestrating the leaks "from suppliers".
2) The suppliers have tested the waters and found Apple "looking the other way".
3) Apple's long time advocates in the industry, or the writers like Walt Mossberg, David Pogue, et al, that were the anointed ones by Steve Jobs during the early days, then continuing till Steves passing, are the ones behind some of this.
There's too much to be gained in page views for the sites, and too much benefit from the buzz for Apple. It's simply not a case of Apple sitting back aimlessly, allowing this to happen.