Potential twist (SPOILERS)

!So, I've seen many people say that the train derailment isn't a premonition from Stefani and that they die at the ending. But also many people are saying that there's more to it. I know Stefani tries to kill herself and that Charlie saves her but it turns out that she was just unconscious. Is that really the twist? Because people are also saying that it leaves room for a sequel. Well every movie does that. If there's more to it, could it maybe be that someone else has a premonition of the train derailment? I can't really guess how there's more to it than something like this happening? Because the whole 'we broke the chain but apparently we didn't has been done almost in every movie', so that wouldn't really be a surprise. I've never seen so many contradicting post about a movie as this one haha.!<