In an interview with Total Film, Dwayne Johnson spoke about possible DC Comics film roles and he said that he and DC will have a big announcement very soon.
Johnson said: "There's a character out there that we're going to announce soon. He has the power of Superman. And it's not the Green Lantern by the way. Believe me – Jon Stewart – he is a character who I wanted to play, but there was already a version of Green Lantern, and so now we've gone in a slightly different direction. But this character has the power of Superman. He can throw down. Just say the word. That's all I'm going to say."
Total Film suggests that "just say the word" could be a reference to the fact that Billy Batson just has to say the word "Shazam" to become Captain Marvel. The character has a power level similar to Superman's. It's possible that this announcement could happen at Comic-Con.