Are there any properties that are safe from Hollywood's incessant and increasing desire to extend or reboot? Obviously nobody is going to make a new Hudson Hawk or John Carter, so limit your consideration to movies that were legitimate hits or cult classics. The most likely candidates would be instances where the original author/creator retains a good deal of control over the franchise.
Lord of the Rings -- not sure on this one. The Tolkien family is super-protective of their rights and hates the Peter Jackson movies, so they will probably never sell off the rights to other Middle-Earth novels. I'm not sure if WB/New Line owns the rights to Hobbit/LOTR in perpetuity, and if so they could simply re-make LOTR again (this time - three movies per book!).
Harry Potter -- JK Rowling holds the keys to the castle. She's developing a new film in the same universe, but not a direct prequel. As with LOTR, it seems uncertain whether or not WB could simply remake the Potter/Hogwart's books but it seems unlikely that they would be able to do prequels or extensions of the story. At the very least Rowling seems like she is done with Potter and Hogwart's, though who knows what her descendants may allow.
EDIT: Thought of a couple more possibilities:
Nightmare Before Christmas -- I'm not sure if this is controlled by Disney on Tim Burton. Burton claims that he has talked Disney out of doing a Broadway musical version, and also talked them out of doing sequels involving other holidays (Nightmare Before Easter, etc). I'm not sure if that means he actually retains ownership of the franchise and its characters, or if he's just somehow able to convince executives that the integrity of the original is more important than new revenue. In a world where Cars 2 exists, this seems unlikely. Perhaps he just threatens to denounce and badmouth any attempt to extend the series/brand.
Interview with the Vampire/The Vampire Chronicles -- I think Anne Rice is probably done with Hollywood, after the way Interview/Lestat films turned out.
Lord of the Rings -- not sure on this one. The Tolkien family is super-protective of their rights and hates the Peter Jackson movies, so they will probably never sell off the rights to other Middle-Earth novels. I'm not sure if WB/New Line owns the rights to Hobbit/LOTR in perpetuity, and if so they could simply re-make LOTR again (this time - three movies per book!).
Harry Potter -- JK Rowling holds the keys to the castle. She's developing a new film in the same universe, but not a direct prequel. As with LOTR, it seems uncertain whether or not WB could simply remake the Potter/Hogwart's books but it seems unlikely that they would be able to do prequels or extensions of the story. At the very least Rowling seems like she is done with Potter and Hogwart's, though who knows what her descendants may allow.
EDIT: Thought of a couple more possibilities:
Nightmare Before Christmas -- I'm not sure if this is controlled by Disney on Tim Burton. Burton claims that he has talked Disney out of doing a Broadway musical version, and also talked them out of doing sequels involving other holidays (Nightmare Before Easter, etc). I'm not sure if that means he actually retains ownership of the franchise and its characters, or if he's just somehow able to convince executives that the integrity of the original is more important than new revenue. In a world where Cars 2 exists, this seems unlikely. Perhaps he just threatens to denounce and badmouth any attempt to extend the series/brand.
Interview with the Vampire/The Vampire Chronicles -- I think Anne Rice is probably done with Hollywood, after the way Interview/Lestat films turned out.