It might be awhile before we see the Inhumans join the Marvel cinematic universe.
Disney/Marvel has undated "Inhumans," which was previously set for July 12, 2019. Now it has no release date.— Ben Fritz (@benfritz) April 22, 2016
The film was previously slated for July 12th, 2019, but according to the Wall Street Journal's Ben Fritz, the film has been undated, and now does not have a release date. This is not the first time the film has been moved, as the film was originally slated for November 2nd, 2018. After one bumping, the announcement of Indiana Jones 5's release date occurring a mere week after Inhumans caused many to fear it would get bumped yet again. Marvel Studios President Kevin Feige alluded to as much during a Captain America: Civil War press junket, and it turned out to be true.
This could be just some restructuring, or it could be due to more Spider-Man films making their way into the line-up. Either way, this project was probably the least anticipated of Marvel's upcoming crop of films. While the Inhumans have made their presence felt on Marvel's Agents of SHIELD, they haven't made the same impact in the films.