well... to be fair the inhumans movie could be the movie that introduces the kree (unless they end up appearing in the avengers film)
Eh....I dunno. I don't think Inhumans would work on its own as a standalone, showing these aliens (Kree) out in space creating a subrace of superhumans and more or less not having that movie interact with the rest of the Marvel Film Universe at all.
I think one of two strategies would be the most logical to introduce The Inhumans into the MFU:
1) Bring Mar-Vell (and Carol Danvers) into an Avengers film (preferably Avengers 2) and introduce him via the Kree-Skrull War. *Then* have the Inhumans come out later that year/next year, with some of the Kree seen in Avengers reprising their roles as cameos.
2) Get the film rights to FF back, and make the new FF film pick up where FFROTSS left off (for the love of god, NO MORE REBOOTS....except in the case of Dr. Doom, whose portrayal in the two Fox films needs to be dropped like a bad habit) and feature the FF's first encounter with the Inhumans on Attilan.
Actually, I think the *best* approach would be in this order:
1) Avengers 2 --- Kree-Skrull War. Mar-Vell and other Kree are introduced. Carol Danvers becomes Ms. Marvel by the movie's end.
2) Fantastic Four "3" --- Marvel Studios gets the rights back from Fox. The storyline focuses on the FF's first encounter with the Inhumans.
3) The Inhumans --- standalone movie, going more into detail on the group.