But there has been a trailer along with positive reaction. Just because you haven't seen it doesn't mean there isn't one. It's not like they don't have material for it and again....their marketing probably won't start until 5 months from release.....just like their last x-men film.
In regard to reshoots, according to the article this info is based on, it's quite clear reshoots are for the "last part" of the film. Not half, not three quarters. No film reshoot take three months to shoot something like that. Even movies that have had 50%-80% re-shot don't take that long in reshoots.

This is
obviously based on scheduling. It was already revealed a month or so ago that Jessica Chastain and James McAvoy won't be available to shoot their scenes until some time in October after they wrap shooting on It Chapter 2.