Anyone fan-crazed enough to read digital photographs of the pages a few days before the real copy comes out is also someone who is going to buy a real copy. And anyone who will read the digital photographs instead of the real book would have borrowed a copy from a friend. My guess is that the publishers will lose zero sales, and that the pre-release will simply increase the press frenzy.
Sounds reasonable but reasons tend to crumble before adaptive ways of life and culture. Already, Asia has developed a sizable culture of photocopied books shared online. In Korea, photocopied books are called 스켄본 (Scanbone) and they have gone beyond BitTorrent and into private storage services. And it's irreleveant whether they are fans or not because shortcuts can easily become a way of life.