I think if you are looking for the movie to follow the Dark Phoenix saga you are going to be disappointed. I got the impression that they were taking the Dark Phoenix story line and combining it with Magneto's war on mankind and then coming up with a whole new tale.
I'm glad they are at least trying to put in more of the mutants if this is going to be the last movie. Sure I'ld like my favorites to get the most screen time, but at least they made the cut.
I'm wondering whose funeral that is they are attending in the trailer. At first I figured it was scenes of Jean's funeral from the end of the movie, but going back and rewatching the trailer, I didn't notice Scott in any of the clips other than the ones by the lake...