Some popular movies and TV shows should have led to sequels or spin-offs that have yet to materialize.Blockbuster films like "Avatar," as well as popular television shows like FX's "Atlanta" are still waiting on sequels or new seasons.And movies that could have led to a franchise, like "Chaos Walking," are also still missing follow-up films.Visit Insider's homepage for more stories.Sometimes it takes longer than usual to get a movie or TV show made.Fans of "Avatar," the highest-grossing movie of all time, is still awaiting the release of its long-planned sequels, a full 10 years after the original film was released.TV shows are susceptible to the long development cycle too. FX is used to long waits for its busy creators of "Atlanta" and "Fargo," while Amazon is spending more than a billion dollars on a "Lord of the Rings" TV show that won't air for another two years.See below for 10 buzzy movies and TV shows that we're still waiting for."Avatar" now has its own theme park, but still no sequels.The biggest movie of all time always planned to have sequels, with director James Cameron saying in 2006three years before the original "Avatar" hit theatersthat he had plans for two sequels should the first one be a success.To call it a success is putting it mildly, but a decade later, "Avatar 2" is still nowhere to be seen.However, progress has been made. The film is now scheduled for a December 22, 2023 release, with "Avatar 3" to follow in 2025, and "Avatar 4" in 2027."Chaos Walking" should've been the next big YA franchise, but there are no further plans for a release.Lionsgate, the studio behind "Twilight," "The Hunger Games" and "Divergent," seemed to have its next YA blockbuster all lined up when it bought the rights to Patrick Ness' "Chaos Walking" trilogy in 2010, but the Doug Liman-directed adaptation seems to be stuck in limbo.The film, starring Tom Holland and Daisy Ridley, was shot in 2018, but it didn't make its planned March 1, 2019 release. Instead, Liman announced reshoots would commence in April 2019.Currently, "Chaos Walking" has no release date.It's been over a year since the last new episode of Donald Glover's "Atlanta."FX is famous for its willingness to let its visionary creators work on their critically acclaimed and fan-favorite TV shows at their own pace.That's great and all, but has led to some long delays between seasons. "Atlanta," the absurd and brilliant brainchild of creator and star Donald Glover, finished airing its second season in the summer of 2018.A third season was supposed to premiere in 2019, but scheduling conflicts pushed that date back. The show has since been renewed for a fourth season, but filming on the new episodes won't commence until 2020.FX's "Fargo" has been off the air for even longer than "Atlanta."The FX effect has had an even bigger impact on fans of Noah Hawley's "Fargo" crime anthology series.Season three of the show based on the Coen Brothers' movie of the same name finished airing in June of 2017. It took over a year just to announce a fourth season would be happening.The fourth season of "Fargo," starring Chris Rock, moves to 1950s Kansas City and began filming, finally, in late 2019. It is slated to premiere sometime in 2020.Neil Gaiman's "Sandman" comic book has been in development in some form since the 1990s.It's hard to imagine a property stuck longer in development hell than Neil Gaiman's "Sandman," which Warner Bros. (the parent company of DC Comics, who released the comic book) has been trying to adapt for the screen for over 20 years.The studio tried for many years to make it into a movie, but when that didn't happen and TV began to become a prestige medium, in 2010 the studio turned its attention on turning it into a series.It still took nine years for real progress to be madein June of 2019Netflix finally announced a series order for "Sandman," with Allan Heinberg as the showrunner.Quentin Tarantino has been talking about "Kill Bill Vol. 3" for 15 years.Will the Bride slay again' Quentin Tarantino has long talked about "Kill Bill" as a trilogy, but though Volumes 1 and 2 were filmed simultaneously and released back to back, "Volume 3" still remains elusive.The filmmaker has talked about the possibility of the film often, sometimes talking up the chances of it seeing the light of day, other times playing down the chances of it ever happening.However, in his most recent remarks on the project, in July of 2019, he seemed to give fans hope again, saying on MTV's Happy Sad Confused podcast, "Me and Uma [Thurman] have talked about it recently, frankly, to tell you the truth, I have thought about it a little further. We were talking about it literally last week. If any of my movies were going to spring from my other movies, it would be a third 'Kill Bill.'"It's been 12 years, but fans aren't giving up on "National Treasure 3" just yet.Disney's family-friendly adventure film "National Treasure" seemed destined for the franchise treatment, but after two hit films, things seemed to hit a snag.After "National Treasure 2" was released in 2007, filmmakers, including director John Turteltaub and producer Jerry Bruckheimer, confirmed work on the second sequel was underway and a script was first completed in 2010.Then, nothing. Disney still hasn't officially given a greenlight to "National Treasure 3," though the filmmakers continue to be asked about the possibility. As recently as 2018 saw Turteltaub reiterating that the script was "close" to being ready."Buffy the Vampire Slayer" has been eyed for the reboot treatment, but will it find a home'It's been more than a year since a reboot of "Buffy the Vampire Slayer" was announced to be in development, but thus far, it hasn't moved beyond the nascent stages.The reboot is said to be set in the "Buffyverse," but will feature a new, black slayer. There was some confusion as to whether the new actress would portray a new version of Buffy herself, but showrunner Monica Owusu-Breen put that to rest in November 2018.Since then, however, it's been radio-silence as to the status of the reboot.A new "Star Trek" series starring Michelle Yeoh' Yes, please. But when'CBS has successfully relaunched a bona fide "Star Trek" franchise to sustain its new streaming service CBS All Access, with "Star Trek: Discovery" anchoring and plenty more series in development.Some in-development shows, like "Picard," which will bring back Sir Patrick Stewart to reprise his iconic role, and "Lower Decks," an animated comedy, are well underway and in production, but a planned spin-off series featuring Michelle Yeoh's character Philippa Georgiou seems to be MIA.The spin-off series, which would feature Yeoh's "Star Trek: Discovery" character as well as an ensemble cast, was first announced in January 2019, but nearly a year later, there hasn't been any updates."Lord of the Rings," set to be the most expensive TV show ever made, is already more than two years in the making.Amazon raised eyebrows when it paid $250 million just for the right to create a TV show set in the "Lord of the Rings" universe, without a story or creator attached, in 2017.Set to be filmed in New Zealand, the untitled "Lord of the Rings" series will be set sometime before the events of "The Fellowship of the Ring" and the studio is expected to spend more than $1 billion to make the show.There is no official release date yet, though Amazon boss Jennifer Salke has said they are aiming for a 2021 release.In the meantime, a writers' room has been assembled, the still mysterious roles cast with actors, pre-production is underway in New Zealand -- and the series has already been renewed for a second season. Click here to read full news..