I don't think that you will stop seeing Peyton Manning commercials even if he doesn't win a Super Bowl. He is the greatest quarterback in the game today. It's the same reason that you see commercials with LeBron James in them... because they are just THAT good.
On a side note, yes, I am personally sick of the Peyton Manning commercials. If I was in his shoes though, I'd do every one of the commercials offered to me. I bet he makes a very nice chunk of change from doing a days work (shooting a commercial).

