Even if Marvel and Star Wars aren't always the massive blockbuster successes they have the potential to be, Disney can call up Big Jim any day to pull in a billion dollars at the box office. However, with Avatar: Fire & Ash "only" grossing 1.4 billion globally at the end of last year, there are reported concerns at Disney about the future of the franchise.
As per Variety, Disney has taken note of the fact that Cameron's third trip to Pandora brought in almost $1 billion less than the second movie. There were multiple factors behind that, such as there not being a thirteen-year gap between Avatar 2 and 3 like there was between the first film and its sequel. However, it appears the Mouse isn't pleased.
One insider noted that "if you make $1 billion on the next movie, you still lose hundreds of millions." This means that there's the potential Avatar: Fire & Ash didn't quite make enough cash to instantly fund the fourth and fifth movies.
James Cameron has said he's fine if he doesn't get to make more Avatar films, but we'll have to see if Disney agrees. It is arguably one of the most-successful franchises the company has right now, and has a track record of pulling in billions of dollars with the mere premise of a return to blue people and CGI vistas.