I keep hearing that but just don't see it. Newt wasn't a character in Aliens, she was a living plot device. There'd be little reason to make her the protagonist since the only two kinds of character she'd become as an adult would be either a Ripley clone or a nutjob. Same reason bringing Hicks back would be lame: he'd just be Kyle Reese all over again.
Happy endings are pretty much a no-no for the characters in this series, all of them.
Happy endings are pretty much a no-no for the characters in this series, all of them.