Ok, forget about everything but the movies, how dearly these movies are held in the public's hearts and how crazy they would go if a new film in this series was announced as being released.
With Harry Potter the real phenomenon is the books, the films are a spin off of those, it's the books that everyone scrambles for and queues up all night for, they are the continuation of the story, the movies are just live action versions for an extra bonus.
So of course it's the Lord of the Rings movies, when the Hobbit is released there will be a media hoopla most akin to the SW prequels, would this happen for a new Matrix? no, X-Men, it isn't. Spider-man? it won't. and the Batman phenomenon was centered around one movie, BB was barely a blip on the cultural radar in comparison, so you can't compare it really as a whole series folk have been following since day one, a lot of people don't even know there was a previous film in that series.