As we all know, you can't retire from football until your body physically prevents you from playing. Something else we can all agree on is that your job is never safe in the NFL, especially in Philadelphia. So watch your back, Donovan McNabb! Here's five players that could be waiting for you to make that one mistake or take that one shot to the ribs.*
Which of these players is most likely to line up under center?
*Please note: This poll is super cereal.