I'm inclined to believe it's true if media outlets other than CNN are now reporting it with their own sources (that is, they're reporting the pending indictments as their own story, not reporting that CNN is reporting the story).
I also suspect the targets of these indictments are people who aren't among the "most likely suspects," too.
Matt miller likens it to a drug cartel or mafia investigation. Rolling indictments
Weissman is an expert at it