Well, we were promised movies for the New Gods and Lobo, but no news about them so far. And I think Black Adam is trying to build up a Justice Society movie if they're gonna have members of the team showing up. I'd love for a Justice League sequel to happen at some point. Also, Hawkman, Teen Titans, and Deathstroke would be awesome.
Though I think I've settled on Martian Manhunter for my 4th. Thanagar can wait till the next phase.