I don't really think a redemption story is necessary for Ellie. It's more than a little implied that by the end of The Last of Us Part 2, she has finally come to terms with quite a bit of what she had been carrying with her throughout both games: Her burden of being immune to the virus and feeling like it's the only thing that makes her life worth anything. Her estranged relationship with Joel being one of the many motivators behind her vehemently pursuing revenge despite all reason telling her to drop it. Even her thirst for revenge against Abby herself. By the end of the game, I feel like she went through her 5 stages of grief, and settled on acceptance. That her actions had consequence, and almost cost her everything.
I also have no interest in a Joel prequel story. I don't feel like there's anything in that story that absolutely needs to be told. A prequel is generally something that builds upon the previous stories, re-contextualizing events from the "sequel" story. To be honest, TLOU2 did just that. It re-contextualized TLOU1. I don't need to play as Joel during the 20 year time period before TLOU1 starts. We already know Joel and Tommy did some fucked up shit that caused their split. They sold that well enough when they met again in TLOU1. Joel's actions throughout that first game weren't entirely heroic, it was just directed at a cause we could get behind (escorting Ellie to the Fireflies to save humanity), as opposed to a more general and generic cause of "It's the apocalypse, and we do horrible things to survive." He brutalized and murdered plenty of people during TLOU1. I don't really need an even less relatable story of him killing innocent people because he and Tommy were raiders/bandits. No thanks.
I'm in the camp of seeing the ending of The Last of Us Part 2 as much more hopeful and optimistic of an ending compared to the ending of the first game, which was a gut punch. I think Ellie is on a path to further recovery, now that she's put all that anger, guilt, and distrust of Joel behind her.
I'd rather have Naughty Dog work on something new for their next game. Then, if they have another story in the TLOU world that they feel is worth exploring, have at it, but I was incredibly satisfied with Part 2. As massive of a game as it is, it honestly felt like two games already. Naughty Dog is an immensely talented studio, so the idea of them tackling a new concept/genre/whatever, is more exciting to me than another Uncharted or The Last of Us (don't get me wrong, I adore both series, but man, I can't wait to see what they do next).
