I fully expect the Saw IP to stay.
It's a huge IP, currently going through a resurgence (Saw X came out last year and was well received, with an 11th film set to come this year). The ride is hugely popular with the wider market, and in general Thorpe Park is known to have "the Saw ride". Sure, it's dwarfed by Hyperia, but it's still intimidating in its own right, and offers a good experience.
Thorpe and Lionsgate/Saw have a good, strong working relationship too to my understanding. The contract has been renewed several times. It must be pretty mutually beneficial too; Thorpe get "the Saw ride" and Lionsgate keep the brand out there and get a nice little paycheck for doing nothing.
I doubt Lionsgate would care that it's dwarfed by a nearby ride, and it's not a ride which Thorpe could realistically turn into an upbeat theme, so it's better for them to keep it dark.