Whether or not the game actually will be his last one, it's clear that he recognizes that he might be and has been taking it all in. Team president Joe Ellis told ESPN that both Manning and defensive end DeMarcus Ware, the team captains, addressed their teammates on Saturday night and were "very emotional and near tears" talking about what the game meant to them.
Manning didn't say whether he planned to retire or not, but it seems to be just another sign that he's well aware that this could be his last game. He said as much to Bill Belichick and Tom Brady after beating them in the AFC Championship game, telling them it might be his last rodeo and that he had enjoyed facing them both so many times.
In other words, it's pretty easy to read between the lines. Though Manning didn't come out and say that it's his last game, the fact that he got emotional and was talking about how much this one means to him, when added to all of the other talk and discussion in recent weeks, seems to paint a clear picture: this one is likely the last game for Peyton Manning.
If so, he'll go out as one of the very best players to ever play the game of football. There's nothing he needs to do to still prove himself, but it sure would be nice to see him go out with one more Super Bowl victory.