So it seems someone found some hidden audio that could either be cut content or a hint of what is to come.

News: GTA 5 audio files hint at casinos, street racing and drug dealing activities - ComputerAndVideoGames.com

Basically, if you can't see the link for whatever reason, it's phone conversations that detail going to the casino, racing for cars, new camera phone features, drug dealing, indoor time trials and ordering very specific hits on people.

Sounds like it all pretty much applies to GTA Online rather than GTA V itself and whispers of Horse races are abound too ( figures with an empty track and empty stables that horses must be a shoe in at some point ).