I don't think there's anything wrong with asking this question, given that the movie does bait at it. I'm generally in agreement with most of the thread that I think it's better overall that Petrie lives. It doesn't actively make the story worse to have him live, unlike something like Chief the dog not dying in The Fox and the Hound. That being said, taking the first movie as a standalone, it could certainly have given both Sharptooth and Petrie even more impact. Sharptooth as successfully killing not only Littlefoot's mother, but taking one of the main kids with him as he's finally killed, and Petrie for essentially being a martyr. It's a sobering thought to imagine a story where the brutality of nature did ultimately.
But I'm just spitballing, and that kind of thing just isn't Don Bluth's style, generally speaking. Even Littlefoot's Mother dying is pretty brutal for his work in the first place, but that's very much necessary in the story. Ultimately, again, probably best that Petrie lives so we can get a happy ending with minimal asterisks and not traumatize the audience even more than they already have been.
