Interesting take on New Mutants.
I don't expect any mutant deaths in the movie though, so the horror angle is kind of an odd fit, but not that odd as NM is often more mystical in nature than most other X-books.
Still, I don't expect this to be a slasher type of movie either. Body count will probably be pretty much non-existent.
Not unless there are other cast members that haven't been announced yet in no-name fodder roles. Everyone in the currently announced cast is a prominent mutant in the New Mutants comics and will probably survive.
Dr. Reyes isn't evil, so she's probably not the villain even though the trailer seems to imply it.
There are two mutants in the movie who could cause the sorts of things we see in the trailer, Mirage and Magik.
Though the real villain is probably Rev. Craig, who may have a role similar to Belasco and is somehow manipulating events to try and kill his daughter and the other mutants. I expect if he dies here, Wolfsbane will be the one to off him.
Could be the Demon Bear thing too, but I think that might be a bit too weird for general audiences, so I kind of doubt it. There will probably be a nod to that somewhere in this, but I don't think they'll really go farther than that.
I do wonder if this will tie to the current X-men timeline or not. There's some speculation that it won't. Though, we've seen Colossus in Deadpool, so there may be a tie in to the rest of the franchise in as Magik is his sister.
There's also the upcoming Dark Pheonix film, which reportedly may also be it's own separate thing from the established X-films.
I'm guessing they'll probably keep it nebulous and tie it in retroactively if it does well.
If they do, it could easily be post a post Logan story as well. Which would fit the title. Might get an X-23 post credits cameo at the end or something along those lines after they escape whatever is going on here.