Right now the Marvel Cinematic Universe is just dipping its toe into the Inhuman waters by introducing the whole concept of "Inhumans" on the less scrutinized platform of TV's [Agents of S.H.I.E.L.D.](series:722469). In fact, it's starting to look more and more like the show is a vehicle for exploring the crazy backstory of the Inhumans in a more friendly, episodic way than would be possible otherwise. Here's hoping that we'll all have it down pat by the time the movie comes around in 2018.
Inhumans or Mutants?
Three years just might be enough time. The short story is that the Inhumans are an extra-terrestrial version of the kind of mutants you see in the X-Men films. A long, long, long, long time ago, the aliens known as Kree experimented on early human beings and that resulted in Inhumans. It's been widely accepted that [The Inhumans](movie:910490) concept would be Marvel Studios answer to the problem of not having the rights to the X-Men characters.
Marvel's Big Picture
In a bold move on the pages of Marvel's comic books, they recently rewrote history to make the characters of Scarlet Witch and Quicksilver inhumans rather than the kids of Magneto so that whole mutant business wouldn't get in the way of their appearance in Avengers 2. In fact, the word on the interwebs is that Marvel is laying down the (non-infinity) gauntlet and any character that isn't in the MCU family could be looking at a very uncertain future in the pages of their comic books.
What the Inhumans movie is being positioned to be is looking more and more crucial to the future storyline of the MCU. It's the movie that could solidify the world that the [Guardians of the Galaxy](movie:424073) introduced with the Avengers world that the more casual fan is familiar with. While the Kree and Skrulls may be old news to Marvel devotees, it'll be a big test as to how deeply extraterrestrial the general movie-going public will want to get with their Marvel movies. Here's hoping they can pull it off because the Kree play a very large part in the Marvel big picture.
Expanding the Universe
While Inhumans offers a great way for Marvel to continue to expand the environment that Guardians of the Galaxy created, the biggest difference is that you don't have a Chris Pratt to ease you into things or the kind of comic relief a Rocket Raccoon or Groot provides. But rumors of Vin Diesel taking on a role in Inhumans, and the fact that there is a teleporting bulldog named Lockjaw, Guardians fans may turn out despite the lack of a human, Chris Pratt-like character.
We can expect [Guardians of the Galaxy 2](movie:1081113) to most likely serve as a lead-in to the 2018 debut of Inhumans. In the meantime, expect to hear more about these "gifted" humans with special powers in Avengers 2, Agents of SHIELD and possibly every Marvel movie until then.