In a twist that the author certainly did not intend to happen, his description of books as an ad-free medium led me to think of a model where out of copyright books are printed with in-page ads and distributed for free. Would that work? :)
One publishing house made the mistake of violating a contract provision against ads by putting a cigarette ad in one of Harlan Ellison's books. Harlan responded in his own inimitable way, as described in the "DID HARLAN REALLY MAIL A DEAD GOPHER TO AN EDITOR?" section of http://harlanellison.com/text/newsfaq.txt .
I like your idea with the out of print books!
Anyway, reading a book requires a completely different mindset from reading a magazine/ watching TV/ browsing the web. So I guess that's why ads "work" in one medium and not the other.