Here's an article from yesterday's (Toronto) Globe & Mail which says that the publishing industry now has a book-sales-scan service similar to what the record industry has had for over ten years.
As a result, the publishers aren't forking over advances for authors who have a track record of unimpressive sales.
The article does not in depth get into what we here know - that mid-listers can now self-publish more easily than ever before. It mentions that publishers will pick up a self-published title that has done well, but it doesn't mention that at that point the author might feel he doesn't need the publisher anymore.
http://www.theglobeandmail.com/arts/...rticle6755208/