Even though WB has yet to officially announce a Ready Player Two movie, Cline would be in the know if an adaptation of his novel is coming. Whether or not Spielberg returns to direct the sequel remains to be seen, but he did help Cline with writing the book, so he likely already has ideas for how he’d bring the story to life with a movie.
During an interview with Inverse, Cline confirmed that development is underway on the sequel. It is in the early stages right now and has yet to be announced by the studio. But Cline seems to believe that most of the original team will return after having a good experience making Ready Player One. Here’s his full quote:
It’s in the early stages right now, especially since Hollywood is in limbo right now. But I can tell from the experience of making the first movie that everybody had a lot of fun.
For what it’s worth, Ready Player One star Tye Sheridan has expressed hope in returning for a sequel movie, while Olivia Cooke confirmed she’s contracted for a sequel too. Now it’s just a matter of seeing if Ready Player Two actually gets made.