While dream casting the adult versions of the characters has been a popular pastime ever since the first IT came out, at this point, nobody has been confirmed to be cast and there aren’t even any significant rumors regarding who is being considered, beyond the possibility that Jessica Chastain could play the adult Beverly, which has been a topic of conversation since just after the first movie was released.
If IT: Chapter 2 is about to get underway, it might actually be just the kids who are going to work for the moment.