Honestly, I'm not sure if Marvel needs either, Inhumans or Mutants, in their shared-universe. Would I mind seeing them? No. We've heard ton of rumors declaring this franchise dead and recently, Kevin Feige, sat down with Empire and had to words to say:
“The only situation right now is that [Inhumans] is not gonna be a part of Phase 3 because Phase 3 increased in a very good way since we initially announced. When and where and how it pops up remains to be seen, but it’s characters we love, it’s a storyline we love, and we just didn’t want to cram it into an already quite full Phase 3.”
WHAT DOES THIS MEAN?
ABC's Agents of SHIELD deals heavily with Inhumans and most of us thought that that's why the movie was scrapped in the first place. At the same time, it makes sense that it just wasn't the right time to release something as complex as The Royal Family.
Kamala Khan is a Pakistani-American that lives in New Jersey. She idolizes Captain Marvel and she's easily one of the standout characters in Marvel Comics. First, let me give you some background on the Inhumans.
Basically, The Kree, experimented on humans to see if they could be weapons to help serve their empire. The Kree thought the experiment was a failure and moved on. Yet, they survived liked that one song from 70's and are now in the forefront of Marvel Comics. They go through a process called Terrigenesis and emerge from a cocoon as an enhanced-individual.
There was a Terrigen Bomb and almost killed all the Mutants in the comics and they also became sterile. Many people thought this was a way for the comics to focus on The Inhumans and push the Mutants out for good (they're owned by Fox). With the exceptions of, Wolverine and Deadpool, because they're awesome characters! Yet, there are quite a few books still dedicated to X-Men.
MY THOUGHTS ON WHAT THEY'RE DOING
I believe they will use their most popular Inhuman to introduce the world to these people. Kamala Khan is one of the most amazing characters currently at Marvel Comics. After reading her comic, you realize they struck gold with one of the most like-able characters I've read in a very long time.
By pushing back their release date, this gives more time to introduce, Captain Marvel and it would only further enhance why Kam looks up to Carol so much! I much rather have her be the one to introduce us to this new world. Her comic book is among one of the best-selling at Marvel and this would be a smart move! Oh yeah, she's kinda like Mr. Fantastic in her power-levels!
The only other reason I believe Marvel is moving back The Inhumans: I believe they're waiting for Agents of SHIELD to be off the air. Television is fickle business and you never know what next season holds. If AOS is gone for a couple of seasons, then a lot of people would forget a lot of the things they set-up and Marvel Studios can start from scratch. I'm not sure if this is right, but it kinda makes sense!
I'm not sure when Marvel will release The Inhumans, but I think it'd be a shame to not include Kamala Khan in Phase 4. She is one of the most unique, funny, unselfish, and badass characters to come out in recent years. A lot of people would like her to have her own TV show, but she's far too popular and deserves the big-budget treatment.
I understand where Feige is coming from about pushing this movie back, but if their are no Inhumans, then the MCU will miss out on a lot of awesome stories to tell. I'm curious to hear what you think of this subject matter and have a marvelous day!