Can MOOC's sell textbooks? King Gillette and the Razor Blade

Jennifer Howard's article "Can MOOC's Help Sell Textbooks?" raises some interesting issues, to wit: if  MOOC's are supposed to be gloriously free for everyone, is it even ethical to require a textbook? A snippet, with some pieces removed: 

But online courses do have recommended-reading lists, and enrollments in the tens of thousands. If even a small percentage of those online students buy books, the sales could add up to a nice boost for a textbook. 

"We are actively tracking the development of MOOC's and believe they do represent a promising market for university-press titles," said Ellen W. Faran, director of the MIT Press. 

Online-course providers continue to draw the line at required reading, and instructors—including those with books to sell—have abided by such guidelines, at least so far. 

"We do strongly urge instructors not to require any textbooks that cost money, since we want the courses to remain accessible even to students that cannot afford to purchase a textbook, including the many that don't even have a credit card," said Ms. Koller, of Coursera, in an e-mail interview.

So it does seem to be profitable to have a MOOC that recommends or requires a book, since "strongly urge" does not mean "prohibit." That's assuming that the student chooses to pay for the printed version instead of reading the book online at flatworldknowledge.com  (or, if it's not there, probably illegally uploaded to a web site). I'm assuming a worst-case scenario here, in which textbooks are required.

But isn't this the same issue as an instructor requiring students to buy the book that ze has written, multiplied by 40,000 instead of 40? The common wisdom on that, which I've gleaned through conversations with others and lurking on the Chronicle's forums, is that if you require a book through which you receive a financial benefit, even if it's the key textbook on the subject, you're supposed to remit the royalties to the students, donate them to a student fund, or otherwise ensure that you don't profit from having the power to require students to purchase the book. How does that work when you have 40,000 or 100,000 students in other countries? One principled professor (can't recall his name) got the publisher to agree to distribute his textbook for free to his Coursera students, but that apparently isn't the norm.

This does answer one question I've had about MOOC's: how will they make money? Here's an analogy. The story goes that King Gillette,* when he was trying to get men to adopt the safety razor rather than the straight razor, decided to give away the razors and charge for the razor blades.  Because they couldn't use the razor without the blades, he'd have them as customers for life, so it was worth taking a loss on the razor to sell a man blades for the next 50 years.  Printer manufacturers do the same thing today: they all but give away the printer and charge a hefty fee for the printer ink cartridges. I wonder if the maker of those machines that use those little coffee pods that are so fashionable now uses the same model, but I haven't looked.

So you lose money on the course, because it's free, but you make money back on the peripherals: you charge for the exam that students take for certification, for textbooks, and, I'm betting in time, for access to the bulletin boards through which the discussion is conducted, since that is already a model being used in traditional universities.

And say you're an elite university: let's call it MegaBucks U. You're the only kind that will have the status to offer MOOC courses while other universities, until they're forced out of business, will be pressured to accept MOOC credits.  You'll make money on the tests, which you'll write and contract out for someone else to deliver; on the textbooks, from your university press; and from the increased visibility and good press that MegaBucks will receive by making "the world's knowledge available to millions" or whatever catch phrase is being bandied about this week.

And you still won't allow MegaBucks U's students to take a MOOC course for credit, because that would be very wrong and dilute the brand.

Again, I ask you: what am I missing here?

*Wikipedia says he wasn't the first to do it, but he's the most iconic figure, so I'm sticking to the analogy.

Edited to add: I am not categorically opposed to any of this, but I really want to see these questions answered.