Everything ebbs and flows in popularity ... funny how some 70s fads/looks are suddenly hip again etc ... even Disney's characters lost a lot of popularity by the 70s and 80s if you recall ... but it didn't affect the theme parks.
People point out attractions like Splash Mountain and Mr. Toad's Wild Ride and ToT etc ... as attractions built on films/franchises that many people have never even heard of in their lifetimes. It doesn't mean the attractions aren't incredibly popular in 2009.
The bottom line is quality.
If IOA does Potter right, then it won't matter one bit if the final film is the final Potter product ever produced ... people won't care. And that assumes no new generations ever watch the films or read the books ... and I doubt that will be the case.
How many kids today love Mickey Mouse, but have never even seen one of his cartoons? A lot more than you probably think.
And while I won't compare HP to MM at this point, I will say the point still makes a whole lot of sense (he says without ego!:lol
Great attractions stand the test of time. Story or characters be damned.
Look at Disney ... PoC debutted in 1967 ... Small World in 1964 ... Jungle Cruise in 1955 ... yet they are all still hugely popular in 2009.
Lilo and Stitch came out in 2002. Was a huge hit. Spawned sequels, TV show and merchandise. Yet Stitch's Great Escape is only still there because it will cost to get rid of it ...
Do you see where I am going with this?
It's ultimately all about one thing whether it's Disney or Universal ... quality attractions. They'll stand the test of time no matter what. Crap, even crap based on very succesful franchises, won't.
It's a Universal truth!
(sorry, it's 2 a.m. and I may be drinking!)