It wouldn't be the middle movie in a Star Wars trilogy without a shocking parental reveal, right? In a recent interview, Vulture asked Daisy Ridley around Rey's parentage, which has been heavily speculated about pretty much since the character was revealed, and will only be speculated about even more fervently in the run up to Episode VIII. Ridley answered:
We will see in a year. Just sit tight on that question.
Thus seemingly indicating that fans will learn about her mysterious backstory in the next mainline Star Wars film.
Now bear in mind, she doesn't outright say that Rey's parentage mystery will be solved in Episode VIII -- her implication could just as easily imply that specific characters, such as Luke, could be ruled out of being related to her during the events of the movie (the interviewer was specifically asking her if Rogue One's Jyn Erso was Rey's mother, or if she's the child of Obi-Wan Kenobi, for what it's worth).
In the past, Ridley has dismissed the desire to learn about Rey's parents as being unimportant to the character's journey -- but considering the constant speculation about it, it's definitely something fans want to know. Could we get a definitive answer in Episode VIII? We'll have to wait and see.