It seems the term 'long gestating' was made for Sin City 2. Robert Rodriguez's follow up to his 2005 anthology crime thriller, based on the series of comics bearing the same name from Frank Miller, has been rumored and talked about for the last 7 years. It seems like every year Rodriguez says that production will start "soon", and now he's at it again. Talking to The Hollywood Reporter, the Texas based director says that once work ends on the April starting Machete Kills, production will likely begin on Sin City 2 in the summer. While I'm not entirely convinced, this is the closest we have gotten to the project actually happening, so fingers crossed.
There is no word on the stories that the sequel will contain, but there was talk before that the tale A Dame To Kill For, a prequel the Clive Owen story from the original, would be featured, along with two new stories created specially for the movie.