Just yesterday, we found out that Shazam! would be the next movie from DC Films, going into production in January or February 2018. That's despite the film not yet having any stars, and only just hiring director David F. Sandberg. This means Shazam! is leap-frogging The Flash, which was originally on the schedule for 2018.
But if you've heard of Shazam because of the DC Extended Universe, chances are you've heard of it through the casting of Dwayne "The Rock" Johnson as Black Adam. Black Adam is another individual touched by the power of the wizard Shazam, though he gained the power millennia ago, and is powered by Egyptian gods (as opposed to primarily Greco-Roman gods). Unfortunately, you won't be meeting The Rock's character in this movie.
"We haven't announced any casting yet," DC Films co-head and DC Entertainment CCO and President Geoff Johns told Yahoo! Movies. "But Dwayne isn't going to be in this movie. He's still doing Black Adam, but he won't be in Shazam!"
Black Adam has been portrayed as both Shazam's primary villain and rival, and also as an anti-hero, which is the more likely path they'll be taking for the character in a solo film, at least at first. The idea, then, is to develop a bit of a side trilogy, featuring Shazam! then Black Adam then finally a showdown between the two -- though Johnson has previously said he's more interested in facing off against Henry Cavill's Superman.
Who might Billy Batson, aka Shazam, face off against in his first solo film, then? His other primary villains are Doctor Sivana and Mister Mind. The former is a genius scientist intent on stealing the power of Shazam for himself. It'd be interesting to pit an aged super-genius who otherwise has no real powers against a superhero with immense power who inside is actually a teenage boy, though.
Mister Mind is literally a worm from the planet Venus. This worm has extreme inteligence, mind control, and telepathy, and is nearly unkillable. How do you depict a killer alien worm on screen against a Superman-style superhero? We have no idea, but we'd like to see them try. Mister Mind was also a member of the Monster Society of Evil, giving them other options for characters.
Regardless, by not going with Black Adam in the first Shazam! film, we at least know that we won't fall into the trap of the doppelgänger villain that so many superhero movies, especially origin stories, rely on (Iron Man/Iron Monger, Hulk/Abomination, Superman/Zod, Doctor Strange/Kaecilius, and on and on).
Shazam! is in preproduction now for early 2018 principal photography and a 2019 release.