1. AHS
The best way to handle AHS, from becoming another WD, would be to bring the house back next year. Obviously, the house will be a mashup of Asylum, Coven, and Roanoke. Then make the property show away till HHN 30.
2. Halloween III
Since HHN did Halloween in 2014 and Halloween II in 2016, the event could wait until HHN 28 to do Season of the Witch. Unless the two year wait was just to stay in sync with Hollywood.
3. WD
The property, like everyone has been saying for years, really needs to vanish. Even more so with AHS, but I could see them doing it. There will be a lot of material with Negan. I could even see them doing an extreme house for with recreating the end of S6/beginning of S7.
4. Trick 'r Treat
5. The Conjuring/ The Amityville Horror
I know Aiello debunked the (clever) rumor. He could be lying though. There's no chance he'd confirm that this soon. If not an Amityville Horror house, they could just be planning to use it in for Conjuring, since The Conjuring 2 starts out in the Amityville Horror house.
6. Ash vs. Evil Dead
The show, as far as I know, is doing well, and the last Evil Dead house was well received. They could even do mashup of the trilogy and show.
7. Vamp '55 house
8. Original
9. Original
Not sure about the last two. I hope it's 5 IP's and 4 originals though. I don't think it'll be, but that gives the event more of a balance. 5 original and 4 IP's is asking too much though.
Not sure about scare zones, but they should mix up how the Central Park and New York scare zones are done. HHN 25 did the block party, which was amazing. Most of the time, recently, those zones are becoming repetitive.
Shows:
Bill and Ted (obviously)
(Maybe) Academy of Villains. I know AoV do other shows, outside of HHN, but the show was so well received and defied everyone's expectations. They might want to hold off with having the the same two shows, but 2013-2014 did it with Bill and Ted and Rocky Horror.