Joss Whedon is solely responsible for Batgirl being developed as Warner Bros. was not considering a Barbara Gordon standalone prior to his pitch. WB has been working quickly to establish and expand the DC Extended Universe to rival the box office success, audience admiration, and notoriety of the MCU and other big franchises. In doing so, team up films like Batman V Superman: Dawn of Justice, Suicide Squad, and Justice League have been put at the forefront of their slate, each introducing new characters and furthering the stories of others.
While these films have received a lot of attention, WB has also been looking at standalone films that could turn into franchises of their own focusing on the DCEU's biggest stars. With Batman, Flash, and Cyborg waiting on theirs - while Superman and Wonder Woman are working toward sequels - Batgirl was one project that was announced out of left field, and now we know why.
Variety reported in a new article detailing WB's multiple Joker films in development that Batgirl was not a film they planned to make anytime soon. As it turns out, they weren't considering it "until Whedon confessed to his love of Barbara Gordon and her masked alter ego." Since that pitch, it has received an official green light and Whedon has been working toward it ever since.
On one hand, this is an example of Warner Bros. altering their plans to work with a talented director that is obviously passionate about one character in particular. Whedon's development of Barbara Gordon's film has been slowed thanks to him taking over directing duties on Justice League, but he won't make it so his future heroine will debut there. It also gives WB another leading female superhero to follow in the footsteps of Wonder Woman, while doubling down on Batman characters in the process.
However, this could also show that WB is lacking a plan to begin with or continuing a reactionary tendency that brought about a drastically different version of Suicide Squad than many expected. Considering they have yet to announce a release date for the movie and won't start production till 2018, it could be some time before Batgirl sees the light of day. With recent news of his personal life resulting in some questioning if he should stay with this project in particular, Batgirl could once again be out of the developmental stages should that happen. In the meantime, fans of the character (like Whedon) will have to wait and see if WB's decision to move forward with Batgirl just because of Whedon proves to be a good one.
Batgirl is currently in development and does not have a release date.