I believe last year's lineup was fairly poor, even by Chessington's standards. If I remember correctly, they had Curse Of The Lost Tomb, which had its entrance where the entrance to the Explorer Outpost Restaurant now is in Wild Asia, alongside Trick Or Treat Wood, which ran in the field to the east of Hocus Pocus Hall. I haven't properly investiagted, but it may be that the explorer outpost restaurant blocks the Curse route, which may lead to a new attraction. I'd expect Trick Or Treat Wood to return, possibly with some Gruffalo tweaks.
Some things I'd like to see which may actually happen:
Bring back The Mystery Of Hocus Pocus Hall
Extend the event so that it covers the weekend before October Half Term as well as the half term week - the event was only about 10 days last year!
Extend closing times to 9pm on peak nights
More family-friendly attraction down the Haunting In The Hollows route, a bit like the 2011 era.
The return of and possibly a step up in the roaming actors around the park.
The return of a kids' show in Adventure Point, like when we had Boo in Market Square.
The return of that beautiful IMAScore soundtrack they had blasting around the park for Howl-o-ween 2014/15.
Not too sure about the 12+ maze personally. If you look at the average Chessington Howl-o-ween guest that goes into the 8+ attractions, they're usually 12 years old at most, so I do question whether there's the demand for it. I personally thought Haunting In The Hollows from a few years back was quite extreme for how they marketed it and I could see something on that scale being added, but I think a full-on scaremaze is unnecessary.
Rides on Dragon's Fury since SRQ installed:
2016: 17 | 2017: 35