We debated back and forth on the 2016 NFL Season Thread about this so I'm not going to rehash my entire argument, but go back and look at his time at Auburn. He was successful because he ran to set up the pass.
It's all well and good to say "Father Time will catch up to him" but so what? So what if in 4-5 years he loses a step? He isn't going to cut it as strictly a pocket passer. That isn't his game. He isn't Jameis Winston who is a pocket passer first, second, and third, but will look to run -- and can do so effectively -- only when they play breaks down. Cam is a true dual-threat QB, maybe the best dual-threat QB the NFL has ever seen not named Ron Mexico.
To restrict him from running is a dumb approach. I'll go on record, if the Panthers continue to restrict Cam from utilizing his legs, the Panthers won't win a playoff game the rest of CM's tenure there.