From Cinema Blend:

“If it’s going to happen, it’s going to happen this year,” Rodriguez just told the assembled Comic Con crowd of Sin City 2, which he says is still in the script process but promises he and Miller are as close to making it as they’ve ever been. He’s basing it on three separate stories by Frank Miller, who co-directed the first movie and whose graphic novel inspired the original. One of the stories is called “A Dame to Kill For,” another is called “The Long Bad Night,” and the third is being kept under wraps for now.