Regardless, Avatar built a strong sense of community among the Na’vi, and now that Jake has been permanently turned into one of those aliens (well, had his soul transferred into his avatar, anyway), he’s part of a new family.
Cameron didn’t clarify whether Jake Sully and Neytiri would already have children when Avatar 2 begins or if we’ll see this family grow over the course of the sequels.
If it’s the former, that rules out Avatar 2 taking place directly after the first movie.
As Jake and Neytiri face new challenges together, they’ll also learn what it means to be good parents, which is just as important for the Na’vi as it is for humans.