I think they'll move Wolverine back. It's a bit of a risk to drop a movie like Gambit in the Summer when all the really big blockbusters are coming out. GOTG Vol. 2 and Star Wars Episode VIII are coming out in May. Can you see Gambit making any money when it has to go against those two?
The safe bet is to put Wolverine against those movies because it's already established as a series, as well as the fact that there's a lot riding on Gambit compared to Wolverine 3. Fox wants Channing Tatum to become either one of the new leads or the main lead for the X-Men films and if Gambit doesn't work that might not happen. Wolverine 3 is just meant to close the book on Hugh Jackman's character, the previous lead of the X-Men films.
Another option is to move one of them into September 2017, because there's nothing there except for a LEGO film about those stupid Ninjago figures.