The radio stations and other content from the DLCs are making constant references to the 2008 recession and financial crisis as a thing that's happening and there's even a news report about how lazy 20-something millennials are complaining that 8-hour workdays don't leave them enough time to play with apps on their iFruit phones

Luis from the Ballad of Gay Tony has a touch screen phone while Niko starts out with a something that looks like an old Nokia and every NPC on the street has cellphones with bleeping ringtones

For reference, GTA IV came out in April 2008 while the first story DLC came out in February 2009