I do agree with the sentiment that one of the big losses if the park were to completely move away from the Haunted House theme would be the loss of the ride's facade, which is basically still one of the best in the park, even 30 years later. Personally, I'd like to see them tell a different story that still fits within the Gloomy Wood vibe.
If I were redoing the ride, I'd go with a witch-based theme, which isn't really a theme the park have previously included (the odd Scarefest attraction aside). If you'll indulge me for a moment....
A trio of twisted sisters have made Gloomy Wood their home. They've banished the ghouls from The Haunted House and are now busy creating their own mischief in this secluded corner of the park.
Needless to say, the guns and LEDs are long gone. The ride itself retains some of its original scenes and mechanics, but significant portions are reworked to implement a new storyline and new spooky surprises throughout.
The new story is reasonably lightweight and leans on a traditional witchlike story - you are exploring the witches' cottage and merry mayhem is unleashed when you are discovered and are hunted down by the occupants.
In keeping with the new story, much of the mansion aesthetic of the current ride is updated to more of a 'medieval cottage' feel. For example, in the grand hall towards the start of the ride, the marble columns and floor give way to wooden rafters and straw strewn across the floor, barely disguising the pentagram hidden below as the car passes over. At the far end of the hall a cauldron bubbles ominously, drawing the riders' attention, before the first witch swings out (using the existing mechanics for the current first flying demon). The second demon is removed, replaced instead by a cackling second witch flying overhead, swinging over the track.
The car takes you into a new scene: "the witches' kitchen", which you are pursued into by the witches, who are preparing to have you for dinner. This is the old crash columns' area, leading up to the trommel, but the room is now much more spacious with the wall to the right of the track replaced by a long kitchen table, where various implements and knives are busy chopping and doing their work completely on their own with no one in sight, as if my magic.
Directly in front of you is the hearth with a roaring fire, it seems like you are going to end up in the fire, but the car turns at the last moment, rounding the end of the kitchen table. At this point there is a jump scare caused by a startled black cat which was concealed behind the table. You make your escape into the trommel that simulates your descending into the basement.
At the far end of the tunnel, a door opens at the top of a new spiral staircase (where the opening face currently is), revealing the shadow of a witch as she pursues you downstairs. You flee through the basement and in the scene where the Giant's face once resided, one of the witches now burst through that window. She asks if "you like her itsy bitsy friends?" and dangling from her fingers are spiders handing from webs which seem to be getting larger as they drop towards the ground.
You turn away from her into the dark and you hear her call after you "Or are you afraid of spiders?" mirroring the classic line from the ride. A spell is being chanted in the background as you then go into the hall of spiders, which is retained in more or less its current form.
A little further on in a homage to the past, the original Ghost Corridor from 1992 is back... kind of. Instead of a phantom flying overhead, now one of the witches swoop down the corridor on her broomstick (obviously on a more reliable modern mechanism). And at the end, she overshoots the car and crashes through a window in the new greenhouse style scene, where the riders instead swing right and through a set of glass door into the Ghoulish Garden.
The Ghoulish Garden retains many of it current inhabitants, but the lunatic is replaced by one of the witches. The hearse and undertaker is moved to the very end of the garden, where once there was a cheap zombie lab, but now you are pursued into a dense forest. A cackle echoes through the trees, "welcome to the gloomy wood, where the wild things are..."
The feel of the forest is similar to a modern version of the woods in the original
Snow White's scary adventure, and perhaps some old friends might appear in the section (perhaps a relocated Tigger, for example). The woods are very ominous and foreboding, but in the final scene we discover the witch has come a cropper from one of her own spell and is entangled in a tree that has come to life and seized her.
I think something like that would be a good use of the ride, with a mix of immersive new scenes, retaining some classic scares as well as paying homage to the past. And as a mix of the new and old, it also means that more budget can be invested into impressive new set pieces and animatronics that really bring the ride back to life.