Shawn Fonteno, aka Franklin in GTA 5, has confirmed that he's been working on story DLC for GTA 5.
DLC continuing the adventures of Franklin, Michael and Trevor was confirmed by Rockstar around this time last year, and originally promised in 2014.
Since then Rockstar has been quiet as the priority has been on regular updates for GTA Online, the new-gen versions of GTA 5 and Heists, which are due early next year.
In an interview with Jack Thriller, rapper and actor Fonteno confirms that one of his current projects is working on the DLC for GTA 5 "and that's first on my list to finish that up".
Maybe the DLC will feature the casino etc etc.