See John Biggs at Tech Crunch:
In a perfect world I’d love for a used bookstore to feature any one of my titles in all its ragged, pre-read glory. But I am not a fool. I understand that the opportunity for my books to appear in print in any great number is now over. I will publish books in ebook form and sell them in paperback as an afterthought. There is no benefit to going with a traditional publishing when I can do so much myself and save my sanity in the process.
Soon all writing will reach a central inflection point when “free or cheap” becomes the norm and print is expensive. This will, in turn, reduce the number of books available to bookstores in general and used bookstores in specific. In the end, paying the author will become much easier and bookstores will snuff out like candles in he wilderness. What happens then is anyone’s guess, but it won’t be pretty.