I have 3 predictions so far
Mr. Mind and Sivanna work to unlock the power of the Seven Realms that connect the Rock of Eternity and attempt to resurrect Black Adam... which would set the stage for his movie.
Billy and his adoptive family delve deeper into the lore and mysteries behind their powers, and learn about Black Adam. And perhaps Billy is offered a place in the Justice League in the end credits scene. We also learn how they have the power of the Greek Gods, considering that their all dead.
In a cruel attempt to bring the worst out of Billy, and not get him to oppose him, near the climax, Mr. Mind kidnaps his neglectful birth mother, and threatens to kill her should Billy try to oppose him. He thinks that Billy is too angry at her for abandoning him... only to be utterly shocked when Shazam does the right thing and saves her. This Billy may not be pure of heart like his comic counterpart, and that's a key message in the first movie, there's no such thing as pure of heart. But that doesn't mean we should not do the right thing, even if it means saving the lives of people we don't like, or did terrible things.