This makes so much sense that I'm really thinking it can't be true. If this is true, Sony really has changed, because I would never believe this of old Sony. They obviously have already manufactured or 110% certain that they are going to be able to manufacture PS4s in large, large quantities, so why not release in October, ahead of Black Friday, ahead of Boxing Day, and also to get all of the buyers for Xmas. Only procrastinators wait until December to start buying Xmas gifts; everyone I know starts buying in October or even earlier.
EDIT: Forgot to mention also most likely ahead of the Xbox One, which is perhaps the most important thing.