It used to be that many companies could corner a market and then expect to get paid indefinitely. While this may still be true for some conglomerates, the bell is ringing for many others–including curriculum publishers.
With the ubiquitous educational resources that are available to anyone with an internet connection, the necessity to use traditional textbook publishing companies is gone. With Khan Academy, Codecademy, and YouTube, I don’t see a need to spend millions of dollars on books that will become obsolete in less than a nine and a half month school year.