It's once again being rumored that Man of Steel 2 will feature Brainiac and Supergirl.
The latest Man of Steel 2 rumor comes from 4Chan, and while not the best source, I'll point out that Guardians of the Galaxy 2 4Chan rumors were pretty much spot on.
The Man of Steel 2 rumor has it that:
• Man of Steel 2 has been developing in secret.
• Geoff Johns and Zack Snyder finished writing a story for Man of Steel 2 back in November.
• Multiple writers were approached to turn in a screenplay, including the writers from Watchmen and the 300 movie series.
• Brainiac will be the villain of Man of Steel 2, and Supergirl will be introduced to the DCEU.
The poster also says Wonder Woman 2 is pretty much a done deal, and that while the villain hasn't been decided, both Cheetah and Circe have been discussed, with it said the studio will likely cast a big female lead opposite Gal Gadot.
It's further said early ideas that were discussed for Suicide Squad 2 include Maxwell Lord, Scarecrow or Bane as villains, and that Killer Frost will be added to the Suicide Squad team and Diablo will return.
Regarding the rumor for Supergirl in Man of Steel 2, back in August of last year saw a similar batch of rumors. We also know that Supergirl was introduced in the DCEU through the Man of Steel tie-in comic book, and the Man of Steel movie seemingly teased Supergirl with the open container in the ship. We can also speculate that since Wonder Woman has been a huge success, that WB may want to introduce more female superheroes.