No, Neil Druckmen already announced that part 3 will have different main characters and Ellie will be included as a side character. He didn't confirm Abby would be in part 3. And if they give another perspective from part 2, like, we play as Tommy and then go through all the trouble with Maria...I'm actually done lol
I don't think Joel should be in Part 3 period. He's dead and the memories made sense in part 2 but it won't in part 3 unless we revolve around the same story, but that's unlikely. I wanna see if Abby ever went to the Catalina Island and made it with Lev. They honestly should make a short game like The Last Of Us No Return but we get each characters perspective. Like we get to play as Tommy during the story, Jesse, Lev, and maybe a bit about how Mel got to the aquarium
