If there was ever any doubt, we now have confirmation from JJ Abrams himself that the case is not closed on Rey’s parentage and the subject will be revisited in Episode IX.
In an interview with ABC News (via SlashFilm), Abrams was directly asked if we’ll learn who Rey’s parents are in The Rise of Skywalker, and he responded, “I will say that we knew, going into this, that this movie, it had to be a satisfying conclusion. And we were well aware that that’s one of the things that’s been out there. I don’t want to say that what happens in Episode 8
Source: IGN.com Star Wars: JJ Abrams Says ‘There’s More to the Story’ of Rey’s Parents