From the Hollywood Reporter:
The project from U.K. illustrators Geoffrey O. Todd and Rich Berner intended to raise £25,000 for a book, Back to the Wild, that would share the story about what happened to Max and the creatures he encountered. The book was also going to be dedicated to the memory of Sendak, who passed away a year ago.
But in a DMCA notice that was registered at Kickstarter, HarperCollins indicates that even a proposal for an unproduced work can cross the line.
My issue with the project was less about the copyright infringement and more about the fact that Sendak was so opposed to the idea of a sequel. It just seems to be in bad taste to dedicate a sequel to the very same person who said, "People said, ‘Why didn’t you do Wild Things 2? Wild Things 1 was such a success.’ Go to hell. Go to hell. I’m not a whore. I don’t do those things."
Let's just hope that a few years from now, that HarperCollins won't decide to cash in on the idea. Because, gross.