It is funny though, the promotional material from Cannes say "Coming Soon", not the reported July 22nd date.
http://trekcore.com/blog/2016/05/official-star-trek-beyond-artwork-on-display-in-cannes/
Well, that may be as simple as the film not premiering on a single date all over the world - this being a sign at an international festival outside the U.S.
Anything is posslble, but given that they're proceeding through the early stages of a publicity ramp-up in a very organized manner it seems unlikely that they'd have pulled the trigger if they were uncertain of what they were going to do.