Octy VRS
Nothing yet. R* have apparently registered some domains that would point to a modern day setting.
According to reports, Rockstar Games has recently registered new website domains that sound like they could belong to GTA 5's in-game Internet (assuming GTA V has an in-game Internet, as GTA IV did). The domains are: CashForDeadDreams.com, SixFigureTemps.com, StopPayingYourMortgage.net, HammersteinFaust.com, and LifeInvader.com. If they were indeed registered for GTA V's in-game Internet, then it suggests that the game is set in relatively modern times, since the World Wide Web only became popular in the mid-1990s. Some have speculated that CashForDeadDreams could be a parody of Cash4Gold (or Cash For Clunkers?), that HammersteinFaust is a parody of Goldman Sachs, and that LifeInvader is a parody of LifeLock, or even possibly Facebook.