Thanks to IMDB, Total Video Games, and iGTA5, we might have a heads-up on who'll be playing the lead in GTA V as well as getting a name for the character providing the voice over in the recently-released trailer. I say might because IMDB, while a valuable resources is also on occasion the startlingly inaccurate home for incomplete, speculative/wishful thinking listings for films, TV series, etc. that may or may not have any chance in hell of existing.
Dousing that little bit of cold water on things, introducing the guy in the photo, character actor Ned Luke, who's credited as "Albert De Silva" in the upcoming Rockstar sequel. Luke has a list as long as my arms of stints on TV series and a couple of films stretching back to '84, and I can imagine the appeal of Rockstar to choose someone not especially well-known who's still got some work under his belt.
As for the character of De Silva being the lead in the game, well, again, this is all speculation, based in part on the fact that he's the only credited character on GTA V's IMDB page as well as a recent casting sheet listing some of the roles being filled out for the game. And while some of this jibes with the narration in the trailer--the lead has a family, is an older guy looking to retire--I'm not willing quite yet to peg Albert as the lead in the game, only because its release is so far out but I feel maybe 75% certain TVG is on the money with this one.
We'll see as more news about the game trickles out/is Internet sleuthed like crazy in the coming months.