In the sort of system I envision the author could pull their book as soon as it became popular, but it's unlikely that an author using their own web site or soc

In the sort of system I envision the author could pull their book as soon as it became popular, but it's unlikely that an author using their own web site or social network would be able to compete against the large marketing and delivery potential of companies like Google or Amazon. Perhaps there would need to be a minimum term. Even so a system something like this would be a win-win situation for authors, distributors and readers (and more arguably for the environment in terms of reduced need to chop down trees and transport books around). The distributor could also supply additional services at a cost, such as the ability for readers to have their private libraries in "the cloud" as a dropbox type of system. So I think the distributor would have sufficient scope to add value around the product that an author may not have much incentive to leave prematurely.