Yowzas! That sounds pretty awesome. A Game of Thrones style Inhumans film where the Inhumans become MCU's "X-Men"? Sweet.
Why does this work? First off anything GOT style with warring powerful figures realpolitiking sounds like a fantastic new twist for the MCU. Second, since Marvel/Disney does not have access to mutants they can use the Inhumans as a mutant substitute. That dynamic between the mainstream heroes (Avengers) and the mutants (now Inhumans filling a similar role) has always been an important aspect of the comics. This is finally a way of brining it to the big screen without access to the mutants and X-Men. Let Fox do whatever the hell they want and continually try new inventive concepts on the big screen.
This sounds like a Phase Three winner to me.
MCU vs. DCCU
Iron Man...The Incredible Hulk...Iron Man 2...Thor...Captain America: The First Avenger...The Avengers
Iron Man 3...Thor: The Dark World...Captain America: The Winter Soldier...Guardians of the Galaxy...Avengers: Age of Ultron...Ant-Man...The Avengers 3
Marvel One Shots...Agents of SHIELD...Daredevil...Jessica Jones...Iron Fist...Luke Cage...The Defenders
Man of Steel...Batman vs. Superman...Arrow...The Flash