What happens if Avatar: Fire and Ash doesn’t make enough profit to convince Disney to bankroll Avatar 4 and 5? Creator James Cameron has said he’s ready to walk away from the franchise, adding he’ll write a book to resolve the one thread Avatar 3 leaves open.
Logically, any colonizer will only proceed if they out gun the natives. Otherwise it’s not colonization, but war. And even then in war, the attacker usually figures they have a significant advantage, or else they wouldn’t attack.