This should not be too surprising to fans, as the two characters are strongly associated with the titular team. They will most likely be joined by Barbara Gordon, who rounds out their trio in the comic books; traditionally her role in that team has been Oracle, an expert hacker who acts as mission control, though in the DCEU it is more likely that she will be Batgirl, her more famous role among casual fans.
Black Canary is one of the oldest female superheroes still being published. Named Dinah Lance, she is an expert martial artist who also uses her “Canary Cry,” a sonic scream strong enough to blast opponents away. She is often romantically linked with Green Arrow, though there is no word yet about him appearing in the franchise.
The Huntress, real name Helena Bertinelli, is often associated with Batman and his cohorts. She even has a similar origin to the Caped Crusader, having witnessed her parents deaths as a child―the difference being that her parents were mobsters, and she is more willing to kill her enemies. With the rest of the Birds of Prey, however, she tries to curve her violent tendencies.
According to Cinema Blend, while these characters are all expected, a surprise for comic book fans is word that Harley Quinn will apparently be in the film, with her role reprised by Suicide Squad‘s Margot Robbie. Whether or not the anti-heroine will be an ally or an enemy of the team remains to be seen, but it seems that Warner Bros. is eager to capitalize on the character’s popularity either way.
Rumors about which DCEU movies are being fast-tracked are changing constantly, but there has been a lot of talk lately about Birds of Prey being set up for a 2020 release. Warner Bros. is said to have two possible scripts to choose from; the Penguin is reportedly the villain of one.
There is some indication that the concept for this movie has been merged with Gotham City Sirens (an all-female villain team), though one of its members, Catwoman, is apparently not going to appear.
For now fans will have to wait and see what else gets confirmed.