List so far of upcoming DC movies:
Shazam (April 4, 2019) Dwayne Johnson has signed on as Black Adam. Darren Lemke of Turbo is signed on to write.
Justice League Part 2 (June 14, 2019)
Cyborg (April 3, 2020)
Green Lantern Corps (July 24, 2020) Could feature both Hal Jordan and John Stewart
Sandman (no release date yet)
Booster Gold (Greg Berlanti is rumored to be executive producer and possibly direct. He is also the executive producer of The Flash, Arrow, etc) Channing Tatum was also mentioned as a potential for playing Booster Gold.
Harley Quinn (details in works, may feature one of the female Birds of Prey characters)
Dark Universe aka Justice league Dark (characters involved Zatanna, John Constantine, Demon, Swamp Thing, Deadman)
Legion of Super-Heroes
A possible reason for BC leaving Arrow, is that she is rumored to be in one of the Justice League movies but not Green Arrow.
Daniel Cudmore who played Colossus in the X-men, X2 movies might be good as Shazam. He has the look and build.