Well this is definitely bad news to see. I presume this could mean a very reduced X-Men budget for the next one. And while some aren't feeling Phoenix or going to space, I think doing that over several films is one way to "reset" expectations for the franchise and go in a different direction. If it is just X-Men vs. Sinister, it will be a lot harder to differentiate that for most folks from X-Men vs. Apocalypse.
Oh well. It probably was both hurt by Alice and is in itself saving some face in the press by defeating that film. Nevertheless, this is not great for Fox. The only silver lining is it may force Simon Kinberg to reevaluate his script writing responsibilities. I'm sure Fox is. I also bet this means Lawrence is gone, which while I liked her Raven in the first two films, it is probably best for the franchise if the character departs.
The writing is on the wall: this franchise needs new blood and new direction, because there is still life in it. The question is who that will come from and where will it go.