Who is most likely to break Peyton Manning's touchdown record? And when?
Answer by Jay Wacker:
To me it seems like there is a Peyton Manning, Tom Brady and Drew Brees who are in their mid-to-late 30s and then a big gap in quarterback quality to young quarterbacks in their early-to-mid 20s.
So I took the active quarterbacks who are in the top 250 on the TD list which is a list of 42 that seems pretty inclusive of all quarterbacks who have a chance. I computed the number of TDs they scored per season and then extrapolated the age and NFL season when they would hit 509 TDs. Of course Peyton probably has minimally another 20 an possibly up to 50 TDs in him. Also, the number of TDs varies as QBs change teams with the system and players they play with. The all-time greats don't switch teams that many times and tend to play very well regardless of who is around them.
With this I found the following QBs would reach 509 by the time they were 45:
We see that Drew Brees and Tom Brady stand out by having a chance to break the record in 2019 and then everyone else will require the second half of the 2020s to break it. Assuming that Peyton finishes out this season strong and has another good season, he'll likely be out of reach of these two.
Beyond these two, there is a huge gap that aligns with the general feeling in the gap in quarterback quality. Philip Rivers, Eli Manning, and Ben Roethlisberger are in the distant-possiiblity camp.
In the young-guns camp, there are several possibilities and we'll have to see if these quarterbacks can keep up excellence for extended period of times. Andrew Luck and Russell Wilson have a chance, but also have the short baselines and thus have the best chances to break the record if they can up their TD pace. But this means that Peyton Manning will hold the record for 12 to 15 years if either Luck or Wilson reach it based on their current pace.
It's always possible that rule changes will allow for more TDs in the future. In my opinion, this is the most likely way that Manning's record will be beaten.
But if we're talking needing to change the game to have the record beaten, we see just how good Peyton has been for so long.