No doubt that is true. And, that could explain why the readers of Harry Potter are soon requesting the "real thing" at book stores and libraries.
BTW, Have you taken a look at the "Religous" section at books stores lately? They are loaded with occult material. Book stores are not museums. Those books are on the shelves because people are buying them.
Ask yourself, "What does this say about the culture and future of America?"
It tells me that people are, as always, morons. That occult material's been there as long as I remember, though that's not very long. Certainly before Harry Potter.
Personally, what I pay attention to are the stacks of new children's novels, the thick ones on the front racks with complicated names and interesting stories. Those are the good sign. When was the last time you saw B&N hawking some dreadful teen-angst story about pimples? Kids are reading again, and it's partly because of Harry Potter.
I've made this point myself. The problem is even more accute in the teens/young adult Sci-Fi/Fantasy section.