You have made very valid points and I fully acknowledge Harry Potter for the powerhouse that it is.

However, we will have to agree to disagree -- I think it is very unrealistic to think that Harry Potter will sustain the heightened level of interest it has had for a decade now -- to sustain over the long term. I'm not sure if it will have the lasting power of Star Wars but who knows.
You are very correct in regards to the books, but again there are no new books to anticipate. For one to assume that future generations that may or may not be introduced to the Harry Potter series will have the same heightened interest is a bit far reaching IMO. Harry Potter was a kind phenomena that had everyone in the world reading each chapter simultaneously. Harry Potter books were what I considered highly interactive, as readers anxiously awaited the next volume. Generations of kids grew up with Harry Potter in real time -- it was an experience like no other. It swept readers off their feet and took them on a continuous fascinating journey for over a decade, I get it.
Those who are just introduced to Harry Potter will have a very different reading journey, they wont experience all the hype and buzz surrounding the next new volume -- the midnight releases at Barnes & Noble -- the Harry Potter sleep-ins and release parties. It was really something magical to receive the next new HP novel fresh off the press. Sorry, but having the complete boxed gift set of Harry Potter books with accommodating dvds is just not the same. But, as the saying goes all good things must come to an end and at least for now HP has seemed to reach it's peak.
The Wizarding World of Harry Potter is nothing to scoff at. I never go to Universal but I am planning a trip because of HP. Harry Potter is not going away, I'm not saying that, it will continuously attract new readers and fans but not at level it once did. With no new books and/or movies in the works, its natural to expect interest to dwindle and things to level off. I really wasn't trying to bash HP.
It's just that I think that Disney's new Avatar land is going to crush Harry Potter world, seriously. I'll still visit though.