I've been provided some information about those talks and have been told they include Bane, Killer Croc, Doomsday and Darkseid.
Regarding Doomsday, I'm told more than likely the character will be CGI like the Hulk, and when he is used it will probably be just for a huge fight. That kind of rules Johnson out as it would be considered a waste of his talent.
Dwayne Johnson is also being considered for Darkseid, which could be the Justice League movie villain.
The Rock is also up for the two Batman villains with Killer Croc, said to be the more modern version, as well as Bane.
For those wondering if the Nolan version from The Dark Knight Rises would affect the use of Bane, I'm told they are ignoring Nolan's stuff. I was told the Bane they would have Dwayne Johnson portray would be more in line with the comics. It seems some weren't that happy with The Dark Knight Rises version, so a Dwayne Johnson Bane would be better portrayed. Bane in Arkham War was mentioned.
Regarding Dwayne Johnson as Green Lantern John Stewart, I couldn't get a confirmation or denial.
Some other information I was told today included a possible description of Gal Gadot's Wonder Woman costume and that Batman Vs. Superman will feature the "massive rise of Lex Luthor."