Like Legacy said, if its not a "classic" horror film, they rarely will create a house around it unless the movie is coming out right before or during the HHN run. Sure "Split" is popular now but it doesn't have the settings to pull off a full maze for a new IP that a lot of people will forget come Sept. Of course you always have the odd ball like Krampus last year but Krampus was a little different. That maze basically wrote itself scene by scene with enough scene changes to be worthy of a house. Plus, it was so different that it could easily work.
I think Exorcist was a huge undertaking for them. It's not common that we get a psychological horror/thriller film turned into a house because it is so hard to pull off. They did a pretty good job with Exorcist but it was far from the scariest house last year. Figuring out a way to pull of Split is asking a lot.
Now, I have a pretty good feeling we will be seeing either a Stephen King house or at least an "It" house. Considering the "It" film comes out Sept 8th, it's perfect timing to turn it into a house. Plus, without Twisty or Jack, HHN needs it clown and Pennywise would be perfect! While I would personally love a Stranger Things house, I doubt that will happen for the same reason Split won't happen. Both properties are not true "horror" properties but rather thrillers with a bit of horror. Still, I feel like Stranger Things could be pulled off easier and with a new season coming out on Halloween, and the crazy fan reaction to that superbowl trailer, they just might figure out a way to do it.