The New York Times has a story about books books with an expiration date. HarperCollins seems to take the lead.
At the moment, library books are the target. But how far can other copies be behind?
"Publishers are nervous that e-book borrowing in libraries will cannibalize e-book retail sales. They also lose out on revenue realized as libraries replace tattered print books or supplement hardcover editions with paperbacks, a common practice. Sales to libraries can account for 7 to 9 percent of a publisher’s overall revenue, two major publishers said."
Book borrowing has always "cannibalized"—whatever that may mean—retail sales of books. Libraries were designed to allow people without unlimited funds to read books they would have no access to otherwise.
This changes everything. So much about equal access to books (and knowledge).