He'll be 39... how many QBs really go into their 40s? It can go downhill pretty fast too.
Peyton Manning - 2 years ago he was setting records... now at 39, he's a liability.
Favre - made it to 41. He too had a pretty good 4k season before being dog[Mark May] his last year.
Kurt Warner made it to 38
John Elway made it to 38... not unlike Manning with a Super Bowl but not playing as well and getting regular season support
Marino made it to 38
Montana made it to 38
S. Young made it to 38
Working off this
list, the only outlier I could find was Warren Moon (44)... and 38 seems to be a recurring number.
Nobody would be surprised if Tom Brady is down within the next 2 years. His numbers are still strong, so he could take after Favre or Moon too I suppose.