Off work now, going to just be..a bit more elaborate in my guess.
What I said above, is what I'm primarily guessing, and for more of reasons on IP's mentioned..
-Killer Klowns from Outer Space: The SZ has seemingly been a fan (and creative) favorite, and the creators seemed rather happy of what Orlando did. But the main reason, lies in SYFY obtaining the Film Rights to continue the franchise on their channel. I get the impression, Killer Klowns will come, while in the classic form, also to market for the upcoming film.
- Stranger Things II/Haunting on Hill House: Netflix Originals, as stated before..seemed rather happy with how ST turned out for Orlando. I would imagine they would continue the trend, and bring those two in, as both Murdy and Aiello do seem very interested to bring Hill House to the event.
As far as Eleven Mazes goes, I am not going to put my foot in the guessing game on twelve, but I do see at-least a Maze Count Bump, with a ratio of 6 IP/5 Original. I think at this point, they need another house to help out on crowds, but if they do twelve..I won't be shocked.
Another question to bring up, is Chucky. My curiosity at the doll, stimulates not to the 2019 Reboot in development; but the Don Mancini show being created. One would imagine he and Universal would want to market it in the best way possible.