Too long for who?
The media seems to think that it is up to THEM to decide how long a player should play.
If it were me I would play for as long as someone would allow me to suit up. I would hang on for as long as possible because that time will never come again and I would want to make it last as long as I could.
That's why George Blanda played for 26 years. That's why Johnny Unitas went to San Diego. That's why so many former players wish they had played a few more years. Listen to Fran Tarkenton sometime, he played for 18 years and wished he could have played longer.
What most players miss about the game is not the paycheck but the commeraderie, being on a team with other guys. It is the relationships that most players miss when they retire.
I find it odd when a guy like Jim Brown or Barry Sanders retires at their peak because they have "nothing left to prove". If they only played the game to "prove something" then they played it for the wrong reasons IMO. Both guys tended to be loners and somewhat aloof from their teammates which explains a lot about why they were able to walk away from the game so easily.
Guys who love the game love it because of the competition and the commeraderie, the whole thing of being part of a team, having a role to play, having your teammates depend on you, celebrating a big win with them or drowning your sorrows together after a big loss.
I would watch Emmitt play flag football at the park when he's my age if I could. I still play whenever I can get a game together which is usually flag since I can't get the wimp yuppies in my area to play tackle.
My son (who is 21) loves to play so that afterwards we can talk about the game together (and to hit me of course
we have some major collisions out there since we are usually the two biggest guys on the field).
I say let them play for as long as they can, I will.