My $0.02: They just finished recently making the whole set. The characters and their playing actors are well connected in the minds of the people. They are still cashing money on them from cinemas, DVD and BlueRay sales, rentals and so on. read more
The last Harry Potter film (Deathly Hallows Part 2) was released in 2011 . So it should have been safe to say the remakes were supposed to be made 10 or so years later, around 2021. read more
If you have in mind the remake of the Batman movies (The Dark Knight Trilogy), consider that before them, the previous movies were seen as childish, not worthy enough of the franchise. Things are different with Harry Potter - the bubble is still growing. read more
The first film, of course, had a significant amount of time devoted to establishing the curriculum of a couple professors, though after that the films tended to have hardly one or two scenes within a class, and most of those were abbreviated due to yet another debacle with Harry and his drama-inducing friends. read more