The next 9 movies in the DC movie universe have been announced at Brazil's Comic-Con Experience
In no particular order:
Wonder Woman 2
Aquaman
Flashpoint
Justice League Dark
Suicide Squad 2
Shazam
Batgirl
Batman
Green Lantern Corps
No mention of Gotham City Sirens, Deathstroke or Nightwing movies.
At least for now !
Thanks to Gary Nusser over at the CBSI G+ forums for the info !