I would have said so too, but there were a few indications that there may be a Grove Street/Ballas presence in the game; Franklin's friends wearing Grove Street Colours, Franklin's dog trying to attack someone wearing Ballas colours etc. Possibly just a coincidence, but always fun to speculate.
Perhaps and I wouldn't be surprised if Grove Street and the Ballas are brought back in some form but there's a limited number of options when it comes to fitting colors and they won't use red or blue for obvious reasons.
Band/Artist I've been listening to way too much: Fallon Bowman/Amphibious Assault. https://soundcloud.com/fallonbowman
Either an Easter Egg that slipped in or Grove Street is in the game(either with the same name or different since GTAV is set in a different universe) and they made sure that it was in the trailer to get people talking.
PSN: getyeflask "He had a baseball bat, and I was tied to a chair. Pissing him off was the smart thing to do."