This is a rumor, so take it with a grain of salt. Henry Cavill may show up as Superman in Shazam!.
Revenge of the Fans recently reported that a "trusted source" told them that Cavill is "set to appear" as the Last Son of Krypton in the upcoming David F. Sandberg flick. This decision comes in the wake of numerous internal discussions at Warner Bros. about his next on-screen appearance.
The website also shared that the studio had been tempted to move ahead with Man of Steel 2 after seeing positive responses to the character's appearance in the Justice League test-screening. But it turned out that mainstream reaction wasn't as positive as they originally thought, and they began to have second thoughts about the sequel.
The original plan was to make some major announcements during January, but the studio decided to wait until summer 2018, when they could make the big reveal at San Diego Comic-Con International. In addition, it's "unlikely" that we'll see the movie in theaters in 2020.
According to RTF, the studio felt that Justice League audiences responded positively enough to Superman that they could use him for additional DC Films projects. A number of projects were "jockeying" for a Superman cameo, and Dwayne Johnson has been "adamant" about it.
But the wrestler-turned-actor's schedule is jam-packed, so it will be some time before his Black Adam solo movie even gets off the ground. To avoid the wait, and to "keep him alive" in the minds of moviegoers, Warner Bros. gave their approval for Superman to appear in Shazam! RTF shared the following about his role:
All I've been told, story-wise, is that Superman has had an impact on Asher Angel's Billy Batson. Batson sees the Man of Steel as an inspirational figure in his life, and that seems to feed into how he conducts himself when he eventually transforms into a cape-wearing, square-jawed superhero himself, in the form of Zachary Levi.
Again, take this with a grain of salt. David F. Sandberg hasn't hesitated to use social media to debunk inaccuracies, so if this rumor isn't true, we can expect to hear from him. He recently shot down a rumored list of character breakdowns, and also made it clear that Ron Cephas Jones' character in the April 5, 2019 release wouldn't be called The Wizard:
The wizard is named Shazam in the movie. I just think they're trying to avoid confusion in news/articles.
— David F. Sandberg (@ponysmasher) January 24, 2018