That scenario probably isn't coming up anytime soon, but I did find a source that has compared every NFL Quarterback to a US President. Don't worry, it's not a partisan slam one way or the other. Some of the comparisions are thin at best, but what else are you going to do in the offseason?
Here's what the Bleacher Report.com says about Aaron Rodgers:
Aaron Rodgers had to bide his time before replacing the most popular player in Green Bay Packers' history, Brett Favre. Likewise, John Adams waited eight years as George Washington's Vice President before taking the big job himself.
Favre is in the conversation as one of the great quarterbacks of all time, and George Washington was one of the most influential men in American History. Both had pressure to preform and live up to the reputation of their predecessor.
Adams and Rodgers carved out their own niche in American/NFL history, and paved the way for a successful protege themselves.
Source: The Bleacher Report.com