2. Alien Invasion?!
GTA V has this thing for the weird and wonderful. Whether it's tripping-out after getting spiked by Michael's son, Jimmy, being abducted, or killing off a hoarde of little green men, there are plenty of strange occurrences to experience in Los Santos. If, for example, you take to the hills with Franklin, you will encounter some nutter who ushers you to help him find parts of an alien spaceship. In your own time, of course. So, seeing as though the extraterrestrial are already heavily featured in the game, maybe an alien DLC pack would make sense? It could work, if Rockstar didn't go too far and make it utterly ridiculous, I think that would be pretty nifty.