Sil Weaver is often (mis)quoted as not taking on any major movie picture since filming Chappie in 2014.
ALIEN 5 was on schedule to be filmed with that tweet of a (then) newly designed M41 Pulse rife in 2015
Since 20th Century Fox pulled the movie Weaver stated she was "busy with AVATAR" when eyes turned when it was interpreted that Scott had dropped the ball with Covenant.
As for James Cameron getting funding for Titanic it sounded like a duck to water cause he got two studios to co-fund $200 Million which is the equivalent to $350 Million in today's money and the 3rd most expensive movie of all-time (adjusted for inflation).
Alien 5 was terminated by Dark Fate.
And Battle Angel which Cameron had a hand in, until it bombed and he threw Robert Rodriguez under a bus for it, like he did for Tim Miller.
The studios must be thinking "fool me once, shame on you. Fool us twice shame on us".
I would say Avatar 2 will be Cameron's last chance to prove box office bombs are the work of Directorial errors. But anyone holding their breath for Avatar 2- release date confirmed December 2021? His last movie was December 2009.