Yup.
People don't seem to get how the Justice League dynamic works when they get together. There's very little in the leaguer's solo stories that cannot be introduced in the JLA film as needed. Yes, Avengers did it another way, but where was the benefit, other than that people knew Iron Man and Thor existed and there were some simple connections between films? It's not like The Avengers was heavily tied to the solo films of the characters, or that there was much in the way of character development in the movie. The insistence that somehow it's "cheating" to make a few solo hero films and then a JLA movie is getting annoying. There are many ways to make a DC filmverse happen.
The JUSTICE LEAGUE characters, who have pretty simple powers and backgrounds at their outset, will interact with each other...much the same as they did in THE AVENGERS. Well, hopefully better, and with more depth.
I wouldn't dismiss Millar's statements so quickly.
Bane DID peak in popularity when Millar was in his twenties. Mark Millar was born in 1969. That makes him in his early twenties when Bane was created and showcased in KNIGHTFALL during 1993. I don't think Bane has ever been that popular after that, save for during his time with Ra's circa 1996/1997, which would have also happened when Milliar was in his twenties, as would have BATMAN & ROBIN. So he pretty clearly wasn't lying about that.
The man's a professional comic book and movie writer. Odds are he DOES know professional writers working on other projects.
It's when he talks about being involved in projects himself that you should take it with a truckload of salt.