There is so much more to this article, but this point in particular stood out!

In this model, authors stop carving out rights.  They hand almost everything over to the publishers and give them maximum flexibility to experiment with format, pricing, sampling, enhancements, and territory – BUT, for a very limited time.  At the end of those 3-5 years, everyone reassesses.

If the publisher has done an outstanding job and turned the book into a bestseller,  they might now have to cough up more royalties.  If the publisher has failed to sell the book or exploit some of the rights they were ceded, the author may continue with the house on a more limited basis or may withdraw the book altogether and take it elsewhere.  The author gets far more flexibility and control over the book’s fate than was ever possible with a life-of-copyright contract, but has to accept a full partnership role: the publisher will no longer pay a significant advance or assume the lion’s share of the financial risk.

via Copyright, Ebooks and the Unpredictable Future | Digital Book World.