It'll be fascinating to see how our relationship with books plays out over the next 10-20 years. On one hand, unlike music, books are very physical objects, their content very much associated with their form, used by many as decoration within their home. On the other hand, most of us only read most of our books once. I suspect that many, like me, then hang onto those books primarily for sentimental reasons (along with the slim chance that someone else might want to borrow them, future children might want to read them, we might re-read them one day, but probably never will), but that feels very much like a cultural fad, albeit quite a long-lived one!