In an interview with Gerard Butler, Sin City 3 (which has Johnny Depp's name tied to it, if you'll recall) was brought up. The MTV interview says:
"I could see myself working with Frank again," said Butler. "But, I don't know. Graphic novels are things that I wouldn't do a lot of, so I would have to really choose carefully before I did."
But one movie that the duo already discussed is a future "Sin
City" installment. "At one point, he talked to me about one of the 'Sin City' [movies]," Butler explained. "And we discussed that."
He continued: "There's a kind of cool character I think in the third one, but it was all very kind of soft talk."
If Butler boards "Sin City 3" that would mean that he could star in the film opposite actors like Angelina Jolie and Johnny
Depp, who have previously confirmed their involvement in the third movie. If we could only skip the annoying second installment.
There hasn't been much news lately about Johnny Depp's involvment in Sin City 3 (there hasn't been a Sin City 2 released yet, so that's no surprise) but if anything comes up we'll post it!