I don't think Avatar 2 will beat TFA's domestic (but it will likely make over it worldwide), not to mention Fox has a pretty weak slate in 2018, Disney has Avengers: Infinity War (which could make over $500M), Incredibles 2 (another possible $400M+ grosser), Han Solo ($300M+), Gigantic and WiR2 should do Moana to Zootopia numbers, Wrinkle in Time could break out, Black Panther will breakout ($250M+) and Ant Man and the Wasp should do $200M-$230M. Possibly Jungle Book 2 and Mulan will do over $300M each. Fox only has that, Deadpool 2 ($400M) and New Mutants ($200M-$250M).