That Gambit movie is still happening
Those main movies have generally done decently at the box office but it wasn't until Deadpool that a spin off really landed with audiences, and arguably that's because it was a great antidote to the overblown blockbusters of today.
But Fox isn't about to stop milking the Marvel comic characters that they own, with another spin off in the works focussed on the character of Gambit. In fact, this project has been around for a few years now, with Channing Tatum cast in the main role as far back as 2015 and even appeared with other X-folk at Comic-con. Then director Rupert Wyatt left and things seemed to be falling part.