Everyone needs to remember a few things here.
Terror Tram leaving is conjecture/rumor. It was heavily rumored to be gone last year... it ultimately was not. There's a reason for that: it gets great GSAT scores among the general public. I'll say Hollywood Harry was not the original plan for the tram in 2018.
The Tram does not cost much in way of scenic. Most of the flats and sets have been recycled for the past several years. This year, that extended to costumes and props (i.e. all of the scarecrow, hillbilly, and pig material that we've seen time and time again). The "new" stuff was off the shelf items purchased from Immortal Masks.
My point being: there isn't a tremendous "build" cost associated with Tram. The costs come down to the staffing... it requires a very large cast (bigger than Monsters last year), plus a whole crew of operations folks (including two supervising teams) and tram drivers. It's a large operation; they're probably in some ways thankful that the neighbors force them to close early.
...my guess, and I want to stress I've heard no indication that Tram is going, but if it *were* to leave... we'd simply see more actors in the other mazes and an additional zone or two. They didn't do those tests in Springfield and the Lower Lot on the final night for no reason.