Before I start my theory, let me tell, here I am assuming the protagonist to be the balcony guy. Reason: I don't see why a narrator would talk about his life if he's not going to be the protagonist. The voice matches exactly with his appearance. I know, you never can judge a voice from a face or vice verca - d'oh -, but they match, you know, that's visible. Now, we have seen this balcony guy in two different versions in the trailer - a younger one and an older one. You see the old one narrating his story and the younger one in action. So what does that mean? The man on the balcony should be narrating the tale of his younger days(to someone). It could be like this: You start the game with the old guy telling his story and then you play the missions as the younger one or you complete the missions and see the balcony guy winding up his story in a cut-scene. And now, just take a look at Rockstar's press release: "A bold new direction in open-world freedom, storytelling, mission-based gameplay and online multiplayer, Grand Theft Auto V focuses on the pursuit of the almighty dollar in a re-imagined, present day Southern California." The 'bold new direction towards storytelling' could also refer to this narrative style. What do you guys think?