20th Century Fox has reserved opening dates in 2017 and 2018 for a trio of Marvel-based films, including a sequel to Josh Trank’s reboot of the Fantastic Four film franchise, which is still 15 months away from its debut on June 19, 2015 (see "Best in Shows--Q2, 2015"), and yet another Wolverine movie.  Fox has staked a claim on July 14, 2017 for Fantastic Four 2, and it will be preceded by a third Wolverine movie, which will open on March 3, 2017.  Fox also reserved July 13, 2018 for an as-yet-unnamed Marvel film.
Staking a date for a sequel to the yet unseen Fantastic Four film represents a leap of faith on the part of the studio, given the middling box office performances by Fox’s previous FF films.  Though the reboot has been cast (see "'Fantastic Four' Cast"), it is not yet completed.  At one point it looked as if Fox might give up the rights to the Fantastic Four, but given the current cachet of Marvel-based movies (and the experience of Paramount, which gave up on Iron Man only to see Marvel Studios turn it into a hugely successful franchise), that appears about as likely as a remake of The Lone Ranger.
Of course it is not as if Fox’s Wolverine movies have exactly set the box office on fire.  The recently-released The Wolverine earned a bit more overseas (about $414 million vs. $373 million for 2009’s X-Men Origins: Wolverine), but it brought in nearly $50 million less here in North America where the studio gets a higher share of the take, so it is difficult to see either film as a big moneymaker for the studio, though Fox did a good job on keeping the costs lower on the 2013 film ($120 million).  The 2009 Wolvie film debuted during the first week in May, while the 2013 film bowed in late July.  Moving a third Wolverine film to March is a bit of a risk, though it should make for less box office competition.
Deadline reports that the studio is in no hurry to reveal the identity of the unnamed Marvel-based movie slated for July of 2018, though fan speculation will undoubtedly focus on some sort of X-Men film or spin-off.