The possibility of James Cameron confirmed an Earth setting for Avatar 2 as well, at least in part.
The first Avatar came out in 2009, meaning its sequels are arriving over a decade after the fact–nearly two decades in the case of Avatar 5. Part of the reason behind this delay is Cameron's ambition for the series, both because some of the sequels have been filming simultaneously, and mostly because the underwater filming technology that Avatar 2 heavily relies on hadn't even been invented yet back when the first movie premiered. The significant age of time between the original movie and the sequels poses certain challenges, but it has also hopefully primed to fix problems of the Na'vi and human nature when it comes to the film's characters, setting, and story.
One of the first Avatar's issues is the lack of clarity surrounding life on Earth in the 22nd century when the film is set. Partly as a result of this, many of the film's human characters feel a bit flat when it comes to their motivations for leaving Earth. The allure of Pandora is quite clear, but the other half of the equation–why people are so ready to abandon Earth–remains somewhat of a generic mystery. With Avatar 2 taking audiences back to Earth for part of the story, the series now has the opportunity to rectify this issue by making Earth, and thereby humans, a more complex and fleshed-out presence in the story moving forward.
Avatar's most significant Endgame-level war in Avatar 2, but also to address one of the original film's biggest story holes. In doing so, he can also give the films' human characters more depth and backstory.
Of course, it remains to be seen just how much of Avatar 2 really is set on Earth, and how much of that time takes place in the story's present vs. past. While humans and the Earth's agenda could continue to be major players moving forward, Pandora also has much more to offer. Cameron's technological efforts alone indicate his commitment to making his fictional world even lusher and more fantastical than in the original film, and with all that energy spent on Pandora, it's unclear how much will be left to devote to Earth. It's even possible that humanity has died out by Avatar 2 due to a shortage of unobtanium. Regardless of how Earth features in Avatar 2, however, it's sure to be useful in addressing Avatar's greatest lingering question.
