Late last year we at Superhero Movie News heard that DC Comics was searching for actors to play Nightwing in the then titled Batman vs Superman. This of course was before Chris Terrio took over scripting duties from David Goyer and seems to written out Nightwing as far as we know. Never-the-less we heard that DC was looking at both Ezra Miller (Perks of Being a Wallflower) and Penn Badgley were being looked at by DC Comics in this role. Fast forward a year and DC comics has just revealed that Ezra Miller has since been cast as none other then Barry Allen in both Justice League and a stand-alone Flash movie slated for 2018! Ezra will indeed be playing Barry Allen in this incarnation...
DC comics also went onto confirm that Jason Momoa is indeed playing Arthur Curry in Justice League as well has his own solo film also slated for 2018. But we all knew this...
It's unknown which spot these two films will take in 2018 with the previously announced dates of 3/23/2018 or 07/27/2018. But Aquaman already has two separate scripts in the works which means it's further along then this newly announced Flash film.
Batman v Superman kick-off the DCCU in 2016