They can tease many of their DC movies and that could be enough for a satisfying presentation.
-Aquaman poster & trailer
-Shazam first official photos and maybe even a litlle bit of footage
-WW2 casting news,returning characters and eveb concept art
-Upcoming movies like BoP(characters),Batman,Batgirl (director and maybe actress).
-Maybe even announce some films like developments on The Flash and ,of course,the long awaited MOS sequel.
Other than that,FB2,The Nun etc. Can get people excited.