James Cameron, From his recent Vanity Fair interview
https://www.vanityfair.com/hollywood/2017/11/james-cameron-titanic-20th-anniversary-avatar-terminator-fox-studios-sale
On the fourth and fifth films: “Let’s face it, if Avatar 2 and 3 don’t make enough money, there’s not going to be a 4 and 5. They’re fully encapsulated stories in and of themselves. It builds across the five films to a greater kind of meta narrative, but they’re fully formed films in their own right, unlike, say, The Lord of the Rings trilogy, where you really just had to sort of go, ‘Oh, sh*t, all right, well I guess I better come back next year.’ Even though that all worked and everybody did.”
Should be an interesting read for Cameron fans, at least since it deals mostly with Titanic as well