Harry Potter is already fading away from pop culture prominence. My niece and nephew are just a personal anecdote. They used to like Harry Potter, but now they think that is for "babies". That's what they said. I have all the Potter movies and sometime I try to put them on when they are here but they don't have much interest in them. My nephew wanted Star Wars Legos for Christmas though. And my niece has a Star Wars Angry Birds game she likes to play. So they both still like Star Wars.
This is why personal anecdotes are the worst form of "proof". The Harry Potter films are arguably darker and more mature than the Star Wars films (especially films/books 3-8), hence the PG-13 rating in four of the last five films. The Harry Potter land at Universal does not contain a hint of the dreaded Star Wars "Jar Jar" humor, while the queue for Star Tours 2.0 very much has this sort of humor.
Not only that, but the Potter films, collectively, are better than the Star Wars films. The best film in both series is The Empire Strikes Back, but there isn't a Potter film as bad as any of the SW prequels.
And no offense to your niece and nephew, but if they believe that HP is a "babies" property and choose to play Lego Star Wars and Angry Birds Star Wars, they may not be the best source of evidence.
The Potter books have not been touched on their bookshelf in a long time.
I, a 25 year old male and MBA candidate, reread them recently. So did one of my best friends, a law school student. So did people I graduated from high school with seven years ago. And they were read from hardcovers, paperbacks, and digital Kindle copies.
Two sample sizes, two drastically different results.
Personal anecdotes are a very poor way to determine trends.
There's no new Potter products, merchandise, or projects to keep the brand thriving. Yes, a generation or so of kids grew up loving this stuff and will be nostalgic for it into their young adult lives...but is Potter catching the new kids coming up in its magic?
People are still very interested in any Potter related products. J.K. Rowling's followup, The Casual Vacancy, was the 24th best selling book on Amazon.com in 2012. This book doesn't see the light of day or sells without the Rowling name and fame.
In addition, there are a number of outlets that continually keep interest in Potter at a high level:
-Pottermore
-Potter expansion 2.0.
-Continual Blu-Ray releases of the series (the most recent this past October)
-Potter conventions
-Fan productions (Starkid's Potter musicals) that renew interest in many different forms
-Merchandise sold in many retailers throughout the country (clothing, toys, games...)
-Kindle-format versions released last spring
And Rowling said in late September 2012 that she isn't closing the door on future Potter/wizard themed books.
Not if my niece and nephew are indicative of any trend.
They aren't.
