Looks like Man of Steel is still getting a sequel, despite the fact Batman Vs Superman was supposed to be its sequel instead of a standalone film delving into Justice League. And there may be some however rather flimsy evidence that Brainiac will serve as the villain and introduce Supergirl for her own film follow-up, even though she already has her own successful show, in the form of Melissa Benoist, on the CW.
Speculation from an anonymous source who posted in 4chan.org claims that Man of Steel 2 is being discreetly developed simultaneously with other DCEU properties that have already been scheduled for release. Further, the tipster also said that the follow-up movie will be the entry point for Supergirl on the big screen:
The sequel to Man of Steel has been developing in secret. Geoff Johns and Zack Snyder finished writing a story for the film back in November. Multiple writers were approached to turn into a screenplay including the writers from “Watchmen” and the “300” movie series. Brainiac will be the villain and Supergirl will be introduced to the DCEU.
From an anonymous source such as the notorious 4chan? Sounds like solid evidence to me. Regardless this wouldn’t be out of place as Supergirl is often associated with Brainiac, and the shrunken city of Kandor. Might Kandor appear as well? Still, it’s 4chan, and it’s the Internet and anyone can make any claim they wish, so while it’s not hard to see how this might bear fruition, it’s also difficult to see through the lies and webs of falsehood that ensnare the Internet as a medium of truth.