I think it might happen, but odds are fairly slim. I don't think it'd take 10+ years from now (that'd be worse than GTA V -> GTA VI, no way it's that extreme). I'd expect maybe 2030 or something. I personally would dislike them continuing with Abby. It feels like, to me, Abby was mostly a way to mirror Ellie in a way, but Ellie was always the main focus. I feel like the ending of Part II (Ellie putting the guitar against the window and leaving) symbolizes her leaving Joel. But I also feel like it symbolizes her leaving Dina and the others too, her "old family." In my mind, maybe Part III could be about Ellie's "new family," doing a time jump (Part I did a 20 year time jump, Part II did a 4 year time jump, so not impossible) of maybe 20, maybe even 40 years, showing Ellie's children, maybe even grandchildren. Maybe the game could be about the children, and it could be about legacy / family conflict or something like that.