The same thing that happened to Anne Rice's works after she died. Her estate went "You're going to write us a check for how much?" and then they signed on the line.

[For people who don't know, Anne Rice was very, very controlling of her work and how it was adapted and/or used. She allowed no fandom publications, and was....difficult to work with. Which was her right, it was her work. But she also started a feud with the dude who owns/owned Popeyes Chicken because he refurbished a building in the French Quarter to be a restaurant, and the building had featured in one of her books, and she felt he ruined her book by doing it because she hated his style. Which was kind of tacky, but it was an empty Mercedes' dealership before or something like that. Lady was...unique. Then she died. And her estate has let the adaptations run wild.]