It had already been confirmed that Michael Keaton is going to be reprising Batman for The Flash solo movie, and even Ben Affleck is reportedly on board. With that said, people are wondering if George Clooney was going to make a Batman return as well, but it looks like that's not happening.
"[Laughs] It's funny - you'll notice they didn't call me! Somehow I didn't get that call. They did not ask for my nipples. Listen, there are certain things you never know. This one, I know [laughs]."
Admittedly, Batman & Robin was considered one of the worst Batman films ever, and it was said to be the movie that killed the franchise back in the 90s. Though the consensus is to hate the films, Youtuber Patrick Willems has come up with this video on how to actually appreciate the movies for how they stand out in the entirety of the Bat-franchise:
Though Clooney isn't making an appearance, there are several rumors of other actors who could appear in the film; from Justice League members like Jason Momoa and Ray Fisher to other actors from previous incarnations like Lynda Carter. Word is even coming out that Nicolas Cage is being asked to play Superman from the universe of Tim Burton's Batman. Though he never played the character onscreen, he was set to play the Man of Steel in the canceled Superman Lives. The Flash could be the fans' only chance to see Cage as Superman.
In the meantime, The Flash is set to come out on November 4, 2022.