What if down the line MS releases a 12GB model, with 4GB just for cache (not for games, since 8GB is already in the wild) or something?
I believe Nintendo has done things like this with DS, and Sony with PSP, haven't they? Added non-game RAM to later models.
I dont see how that would be legal under Dsoup's thinking, which is another reason it just doesn't make remote sense (same as what if MS decides to totally reengineer/delay Xbox One?)
What if Nintendo announces a DS XL at a certain res screen, then bumps that res up a little before launch?
What if Ford up their new 4 cylinder by ten HP?
There's so many possible permutations it would be impossible to even enforce this.
Edit: Sony certainly changed the RAM on different PSP's
http://en.wikipedia.org/wiki/Template:List_of_PSP_Models