According to the New York Times, sales of e-books have cooled off. The dazzling arrival of e-books has cooled into the practical, mundane reality of reading. It's not that people have turned against e-books, but they're concentrating on the book, and not differentiating on the platform.
Something similar is happening with phones; while adults and teens are addicted to tiny screens, younger kids are less interested. In part, this is the natural urge to be different from the oldsters; but it's also a lack of tech adoration. These devices are a normal, mundane part of their lives, not magic.