First, let's address the Vin Diesel rumors. Over the weekend, Vin dropped some cryptic hints about possibly joining the cast of an "Inhumans" movie, and if he does end up in the movie, there's a strong chance he'd be playing Black Bolt, one of the main characters in the comics. Here's what makes that sort of a genius-level move on Marvel's part. When they announced Paul Bettany as The Vision for "Avengers: Age Of Ultron," it was not only a great chance to see him onscreen finally after just hearing his voice in the "Iron Man" movies so far, but it also makes sense from a story standpoint. Jarvis is part of the DNA of the creatures that are both Ultron and The Vision.
With Diesel, though, there's no direct relation between Groot and Black Bolt. That will cause problems, right? I mean, the first time Diesel opens his mouth, it'll be obvious that Bolt is speaking in Groot's voice, right?
Well, no. Black Bolt never speaks. His voice is a weapon, and would have to be a processed effect. As a result, Marvel could get the best of both worlds here. They get his voice for Groot, and they get the rest of him, which already looks like a comic book.
The term "Inhuman" is a priority for Marvel these days, both on the pages of the comics and in the Marvel Cinematic Universe, and they laid some groundwork for this project in "Guardians Of The Galaxy." In the comics, the Inhumans are given their powers by the Kree. Those would be Ronan's people, and it's obvious from "Guardians" that the Kree aren't terribly well-liked by other alien species.
There's been a fair amount of chatter about whether or not Carol Danvers, aka Ms. Marvel, aka Captain Marvel, will be showing up sometime soon in the movies, and I think it's a safe bet to say that she will. She also got her powers from the Kree, so it would be a fairly easy matter to bring her and the Inhumans into the same continuity.
According to Collider, Joe Robert Cole is currently working on the script for the film. This is part of the same program that allowed Nicole Perlman to write an early draft of "Guardians Of The Galaxy," which helped Marvel see the full potential of the project. I'll be curious to see if this one keeps picking up momentum, and how Marvel works to incorporate the Inhumans into their larger world.
In the meantime, "Avengers: Age Of Ultron" is next up for Marvel, in theaters everywhere on May 1, 2015.