When you’re at the top of the world, you can afford to be magnanimous, as James Cameron was when Avengers: Endgame passed both Titanic and then Endgame at the worldwide box office, taking the new title of highest-grossing movie of all time. Not only did Cameron congratulate the Avengers team, he later expanded on the subject as giving him personal hope for his many Avatar sequels.
Article source: https://www.cinemablend.com/news/2489881/joe-russo-response-to-james-cameron-hope-for-avatar-sequels-after-avengers-endgame