The short-term threat is that fast high-resolution color copying technology is now so cheap that enforceable copyright is becoming a thing of the past. Publishers will not face threats from large copy stores because they are a large enough target that they can be sued, but now individuals can afford personal copiers. For example, the Canon PC-311 costs $400. And this is not an industry that is about to disappear; worldwide, the copying industry now sells $14 billion worth of equipment, of which Canon alone accounts for $3.5 billion .
Worse, copiers are going to get smaller and cheaper. Electronic storage costs have dropped so low versus printing costs, that a copier can be merely a scanner with a capacious memory. Such a copier could be palm-sized--it would be attachable to a separate computer or printer. Because electronic storage is now so cheap, it is no longer necessary to print pages when the original is scanned.
Over the past 2 decades the cost of a short ton of newsprint has gone from $150 to $550. It is not that paper has become an unsupportably expensive medium overnight, but electronic storage cost has plummeted so much that paper's cost has skyrocketed.
Imagine a world of small cheap personal copiers, where you can rent, then copy, expensive paper books just as you can rent music, software, or movies today. Imagine a world where one student in a class buys a copy of a textbook, then copies it for all the others. Imagine a world where publishers in Pacific Rim and Middle Eastern countries buy one copy of a book then sell duplicates just above the duplicating cost.