Well everyone seems to be making the point that as an old man he would be too weak to attack or something. The entire thing just seems like an issue that isn't worth dealing with, and I think they would most likely just ignore it and keep Snake normal. Hell, by the time SSB4 is released there might be a new Metal Gear game Snake is dead in. Are they going to cut him out just because he's dead? I seriously doubt they care that much. They'll keep in the characters that they want kept in, and they'll use the look that most people like, regardless of the gaming storylines.