Warner Bros. doesn’t do anything without her blessing and J.K. Rowling has said before that Harry Potter and the Cursed Child was always intended to be a play and not a movie.
Not only did the spinoff movie Fantastic Beasts and Where to Find Them allow them to return to the wizarding world, but J.K. Rowling also decided to continue the actual Harry Potter storyline with the stage play Harry Potter and the Cursed Child.
It isn’t hard to imagine that Warner Bros. would really want to turn Harry Potter and the Cursed Child into a movie, given the success of the play and considering that the Harry Potter franchise is one of the most successful of all-time at the box office.
A lot can happen between now and 2026, but for now, Harry Potter fans need to take J.K. Rowling at her word and trust that Harry Potter and the Cursed Child will be a play and nothing more.