No Need to Worry
It is true that there is always entry into the textbook-writing business, which puts incumbents like me at risk. But I am not worried. I am one of the economics profession's leading producers of textbooks, I have an extensive network of dealers (aka professors), and I have friends in high places (Larry Summers, Christy Romer). So doesn't all this make me precisely the kind of too-big-and-too-interconnected-to-fail plutocrat that, if push comes to shove, will get a government bailout?
If you doubt me, let me point out that my initials are GM.