It turns out that the project is very much alive and remains in the planning stages. Forward movement was stalled whilst Nolan and Joy were prepping work on the fourth season of Westworld for HBO (now shooting) and whilst Joy was putting the finishing touches on her debut feature film as a writer-director, Reminiscence, which hit cinemas and HBO Max this week.
According to Joy, the Fallout TV series will be "a gonzo, crazy, funny, adventure and mindf**k like none you've never seen before."
The TV show will be based on the popular video game series which has sold over 50 million copies since the release of the original game, Fallout, in 1997. Subsequent games in the series are: Fallout 2 (1998), Fallout Tactics (2001), Fallout: Brotherhood of Steel (2004), Fallout 3 (2008), Fallout: New Vegas (2010), Fallout 4 (2015) and Fallout 76 (2018), along with various expansions and DLC. Set two centuries after a brutal nuclear war wiped out most of the human race, the games chart the rebuilding of new society amidst the ruins of the old. The series has also spun off a tabletop miniatures game, Wasteland Warfare, and a tabletop RPG, both from Modiphius Entertainment.
The Fallout video game series is currently on extended hiatus, as the current developers, Bethesda (now owned by Microsoft), are working on Starfield and The Elder Scrolls VI. A potential Fallout 5 is unlikely to be released this decade, unless it is given to another studio to develop.
It's currently unknown if the TV show will directly adapt the stories in one of the games, or will be an original story set in the same universe.