Now, a lot of angst over Harry Potter is the fact that the series is over, the fandom is shrinking (or moving on to Twilight and Supernatural -- sigh), and the volume of new HP fan fiction is dramatically decreasing, as is the number of readers and reviewers. The fandom will contract even further once the last movie is out. One by one, the major Harry Potter fan sites are starting to resemble Detroit -- once thriving communities, now being abandoned in droves, with many of those left behind turning the remains into a ruins. (I don't even post on the Fiction Alley forums anymore.)
Contrary to the more dismal predictions, however, I don't think the Harry Potter fandom will ever go away. Even the most obscure series, after all, have their own LJ communities and sections on fanfiction.net. And I like to remember the example of Star Trek, the fandom against which all other fandoms must inevitably be compared, the fandom that spawned fan fiction communities in the days before the Internet, during the long years in which there was no new canonical material being produced. (Also the fandom that gave us terms like "slash" and "Mary Sue," for you kids who don't know that.)
Time will tell whether Harry Potter takes its place as a true classic. Will our grandchildren still be reading Harry Potter? Will it be our generation's Narnia, or will it be our generation's Elsie Dinsmore?
That's probably a pretty bad comparison. I liked the Chronicles of Narnia well enough when I read it in elementary school (and was more inclined to take the fantasy elements at face value, even though I was quite aware that it was a Christian allegory even then), but even as a child I knew that the last book ended the series in a train wreck, figuratively as well as literally. (Well, for some of you vitriolic Deathly Hallows-haters, maybe that is a good comparison.)
Being in another one of my rambly moods, I'll share a few other series and authors that have influenced me. (I'm going to limit myself mostly to fantasy here, though I also read lots and lots of science fiction, too.)
The Dark Is Rising, by Susan Cooper. Frankly, this is a better series than Harry Potter. Will Stanton is a much grimmer boy magician than Harry Potter, and this is the first series I remember reading as a child that made me sad when I finished the last book because there wasn't any more to read. Susan Cooper really deserved to have Rowling's level of success; sadly, the 2007 film "The Seeker" bore almost no resemblance to the source material, and it sucked mightily.
Suzette Haden Elgin's Ozarker trilogy. Yes, Elgin wrote about magical Ozarkers long before I did. My Ozarkers are quite different from hers, of course, but I was undeniably influenced by her, and there are quite a few overt nods to Elgin's Ozarker trilogy in Alexandra Quick.
(I've also read some of Elgin's other works; the Native Tongue trilogy is, well, interesting in the first book, kind of absurd in the second, and incoherent in the third.)
His Dark Materials, by Philip Pullman. Some people have compared Alexandra to Lyra, but I didn't actually read these books until after I'd written Alexandra Quick and the Thorn Circle. I loved the first book, and liked the second; unfortunately, the story kind of fell apart in book three. Why do so many authors screw up their series in the last book? (The movie The Golden Compass, by the way, was really not that bad; it's unfortunate that it bombed so badly that we're not likely to ever see the rest of the series on film.)
The Lord of the Rings. I'm mentioning this one only because it would be a glaring omission. But you know what? I'll probably be pilloried by some folks, but I never actually finished the trilogy. I thought it was boring! Yes, Tolkien was an epic worldbuilder, but as a storyteller, he just did not captivate me. I'm one of those people who knows most of my Tolkien second-hand, from the movies, etc. (Also from way too much Dungeons & Dragons when I was a kid.)
Elric of Melniboné, by Michael Moorcock. Not my favorite fantasy series of all time, but I thought it was much more creative and imaginative than Tolkien. Where Tolkien mostly synthesized a lot of Germanic fairy tales and Nordic myths, Moorcock created something entirely different, including a hero who was not very nice and not very heroic, and who dies in the end. (I know Moorcock didn't invent the anti-hero, but this was one of my earliest exposures to the concept.)
I could go on, but I've run out of steam for this particular entry, and really, I just felt like posting something besides "Hey! Word count update!" (103307, btw.) Feel free to discuss your literary influences. (Has anyone besides me ever read Elgin or Susan Cooper?)