Daredevil and Jessica Jones established the Hell's Kitchen/Netflix corner of the Marvel Cinematic Universe in 2015, and Luke Cage (whose namesake was a supporting player in Jessica Jones season 1) will explore the MCU version of Harlem in 2016. That means there's only one member of The Defenders left to introduce (before that team assembles in a Netflix mini-series): Daniel Rand a.k.a. Iron Fist.
Marvel COO Joe Quesada recently confirmed that Iron Fist is still moving forward, after the lack of official (and/or all-but-official) updates on the project of late helped to fuel the rumors that the fourth of Marvel's Defenders Netflix TV show was in danger of being cancelled. A show-runner has now been officially selected for the series - and there's also a synopsis that sheds more light on the initial setup for the Netflix show, too.
HH and CB broke the story earlier today (at the time of writing this) that Scott Buck will serve as the show-runner on Iron Fist, and Marvel has now confirmed the news via an official press release. Here is the statement from Marvel TV head Jeph Loeb, regarding the news:
“Scott came in with a take on Iron Fist that quite simply knocked us off our feet. We always look for the most creative minds in the field to help us bring our heroes to life, and with Scott we’ve found someone that can deliver yet another great series in the ongoing story of The Defenders.”
Buck, for those unfamiliar, has previously worked on such TV series as Nikki, as well as the HBO series Six Feet Under and Rome, though he most recently served as show-runner for Dexter during its final four seasons. This means that Buck is the second major Dexter alum who has gone on to work behind the scenes on Marvel's collection of Netflix series, after Jessica Jones creator/show-runner Melissa Rosenberg. Buck joins a show-runner team that, in addition to Rosenberg, includes Cheo Hodari Coker (Southland, Ray Donovan) - who's serving as the architect for Luke Cage season 1 - as well as Marco Ramirez (Sons of Anarchy), who's taken over show-running duties for Daredevil season 2 from Steven DeKnight.
The official Iron Fist synopsis released by Marvel (which you can read below) accounts for the character being absent from previous Marvel/Netflix series, at the same time that it teases what he will bring to the table for The Defenders:
Returning to New York City after being missing for years, Daniel Rand fights against the criminal element corrupting New York City with his incredible kung-fu mastery and ability to summon the awesome power of the fiery Iron Fist.
Whereas Daredevil is more of a crime series first, martial arts drama second, it sounds as though Iron Fist will aim to be a martial arts drama first, crime series second - albeit, with overt mystical elements that Daredevil hasn't included so far. The Iron Fist comics have always been firmly rooted in mysticism, so this doesn't come as a surprise; together, Iron Fist and Doctor Strange (currently filming for a 2016 release) will introduce mystical elements into both sides of the MCU (movies and TV), around the same time. It also sounds as though Iron Fist's origins are going to be explored by way of flashbacks, as was the case with Daredevil, Jessica Jones, and (probably) Luke Cage before him.
Moreover, Iron Fist should end up building on the foundation of Daredevil, since that series has already established that there are mysterious organizations from the far East meddling in the affairs of Hell's Kitchen's criminal underbelly. It also seems safe to assume that, like the previous Marvel/Netflix series, Iron Fist will take place in chronological order of the Netflix shows' release dates (e.g. some time after the events of Luke Cage season 1). There's also a decent chance that Iron Fist season 1 shall conclude with Rand and Cage teaming up to form Heroes for Hire - before all of the The Defenders assemble on the small screen. All shall be revealed in time, of course.
Daredevil season 1 and Jessica Jones season 1 are now available on Netflix. Luke Cage season 1 and Daredevil season 2 will debut on Netflix in 2016. Release dates for Iron Fist and The Defenders on Netflix have not yet been announced.