Originally Inhumans was going to be an MCU movie. Vin Diesel was lobbying hard to be Black Bolt. Ike could only destroy them because Feige passed.Ike Perlmutter was the one who petulantly killed off the Inhumans, for now.
Supposedly when Agents of Shield tv show started incorporating Inhumans as a race (not the royal family that the movie was going to be about), Studios wasn’t happy and the movie got pushed to the back burner.
When the Spider-Man deal happened everything got pushed back, and Inhumans taken off the schedule completely. Then the tv show happened. The only way we see any form of Inhumans on the big screen is if they don’t want to alter Ms. Marvel’s (Kamala Kahn) origin when she pops up in a Captain Marvel sequel.