1) Roland Catches Up To The Man In Black
The Dark Tower isn’t going to adapt Roland’s struggle through the Mohaine Desert as he relentlessly pursues The Man in Black, but we do know that the hero will still be tracking his nemesis down throughout the course of this movie. In The Gunslinger, Roland and The Man in Black palaver and the villain puts him on a course which he hopes will lead to his death (the aforementioned Drawing of The Three).
While things will no doubt play out quite a bit differently here, it would be awesome to see this movie conclude with these two coming face to face for a confrontation which by that point feels earned and also sets up the future of the franchise. The Man in Black needs to make it out of this alive though – even if he fakes his death like in the books – because this and future movies have the chance to make up for the disappointing way the villain’s arc ended in the source material.