He says he is still "midway in that saga" with Avatar ("three out of five so far and counting") and that the story isn't finished for him yet. At the same time, he explicitly states:
Later, when asked about his current "why" and how he prioritizes what to do next, he elaborates more fully:
He explains that he has recently mapped this out for himself, starting with the criterion "What will do the most good?" (written in block letters at the top of his list). He is evaluating projects based on how they might improve the world for his kids, while still requiring strong storytelling and characters so the work doesn't become didactic.
He adds that he hasn't made the final decisions yet and is in a "liminal state of mapping out... kind of the last act," and that he doesn't know whether that last act will last a year or 20 years.
Summary of what the video says on this topic
Cameron confirms he wants to tell other stories outside Avatar, is actively weighing which ones to pursue and in what capacity-directing vs. writing/producing), and is using
"what will do the most good" as his primary filter. He still considers the Avatar saga unfinished (currently at 3 of a planned 5), but he is clearly at an inflection point where non-Avatar projects are under serious consideration.

This is a copy paste from Reddit btw

Theres still hope avatar fam

3 sucked.

but at this point i need to see it all the way through.

yeah why was 3 basically a sloppy version of the second movie??

absolutely CRAZY how sloppy it was.

final fight was gorgeous though.