At some point, Aaron Rodgers will be old. Today is not that day, but we're standing at the precipice of the season in which Aaron Rodgers will turn 31 years old.

31 is not old by any stretch of the imagination, but we've almost certainly reached the point at which Rodgers is closer to the end of his career than the beginning.

He no doubt has a few years left in his prime, but "a few" is the operative phrase there. Not "a lot" or "many". Just a few.

Age, however, seems to be even less a factor in terms of affecting productivity today than ever before. The NFL has geared its game to suit its quarterbacks, and more and more are putting up highly productive seasons late into their careers. A quick look at Rodgers' contemporaries shows he'll likely have five to six more extremely high level years before any sign of decline.

Peyton Manning, though showing some declining arm strength, may be a poster boy for quarterback play after the age of 30. Now entering his 17th season, Manning has made six Pro Bowls and has been an All-Pro four times. If not for losing a season due to injury in 2011, those numbers could be higher. Manning has also thrown 30 or more touchdowns five times since the season after he turned 30.

Much in the same vein, Tom Brady has been very productive in his later years, making five Pro Bowl teams and one All-Pro team in the six seasons after his 30th birthday. Brady's accuracy has waned in recent years, especially last season when he posted his lowest mark (60.5%) in about a decade. Still, he remains a top-flight quarterback even in his late 30's.

Finally, it's worth taking a look at Brett Favre, the quarterback to whom Aaron Rodgers will always be compared. From age 31 on, Favre made six Pro Bowl teams and threw more than 30 touchdowns four times, including a league-leading 32 in 2003 at age 34. Did he hang on a season too long? Most definitely. Could he still play well into his 30's? Absolutely.

Injuries will always be a factor. They ended Favre's career and have significantly altered both Manning's and Brady's. Rodgers himself is coming off a broken collarbone and has faced problems with concussions and even a broken foot in the past. But if he can stay upright, there's no reason he can't continue what's been one of the most productive runs by a passer in NFL history.