The reporters are calling again, looking for a new Harry Potter story. I wish I could be more helpful, but there really is no news. When they ask what the "next Harry Potter" will be, I point out that there was no last Harry Potter, depriving us off the crucial second dot from which we might be able to derive a meaningful line. Of course, we've seen book crazes before--Goosebumps, Sweet Valley, Babysitters' Club--and we can look back into the early 1970s to see another children's book that took over the adult bestseller list: Watership Down. But there has been nothing like Harry. And the next one, if there is one, probably won't be about a boy wizard, if the lack of success of the many post-Harry wannabes is any indication.
As for another frequent question, I really have no idea whether Harry Potter will be widely read in twenty years. One journalist floated the notion that once All Is Revealed, the series' cultural capital will be spent, but knowing that Frodo succeeds in his quest hasn't stopped fans from reading Lord of the Rings over and over again. There is an interesting comparison there, I think, but more for its differences than similarities: while both Harry Potter and the Tolkien books are multi-volume fantasy tales of an unlikely hero shouldering the weight of the world, Lord of the Rings for years was what you read if you were cool (at least, that's what its readers thought) or if you were a dork (that's what its scorners thought). The mass-market success of the Peter Jackson movies (and a Harry-wrought fantasy-friendly zeitgeist) might have changed that, but Harry Potter has been a crowd-pleaser from the start. You don't read Harry because that's what the cool kids are reading, but because that's what everyone is reading. (And I've never seen popular taste so ferociously defended. Tell people you don't like John Grisham, fine. Tell 'em you don't like Harry, and it's as if you have insulted humanity.)
The review copy of the latest Harry should arrive Saturday morning [correction: the 20th] at my house, from whence it will swiftly be retrieved by the assigned reviewer. When she's done, then we'll have some news.