It's been widely reported that there will be multiple levels requiring elevators to change grade, similar to the Transformers attraction, which will of course require elevator pits for the equipment. However, I don't think that elevators (even industrial sized) would need to have pits as broad or as deep (based on the shadows) as what they're doing
I think it was
@marni1971 who said that the pit would be part of the attraction's finale, which implies that it will be for some sort of special effect and/or oversized set. Given the ride's subject matter, it's not too hard for me to imagine why they might need sort of deep-but-narrow show space while attempting to escape from the Death Star...