Another reason paper books won't be replaced by electronic ones anytime soon:

. . . commercial e-books come with a checklist of permissions that were unheard of in the creaky days of pulp and ink. Depending on the book, you may not be able to lend it to a friend, print out a page, copy and paste a passage into a term paper or even read the book aloud. None of these would violate the copyright, but anyone who hacks the e-book’s software to perform these legal acts violates the law.