I could easily seeing him being a coach. He is obviously an intelligent guy whose most valuable asset on the field is his brain. He understands the game and played under a great coach. He also seems to have a very strong relationship with teammates, is very mature for his age, speaks well, and is a great ambassador of the university.
Not knowing CK whatsoever personally, he strikes me as a person who would make his future career decision not solely based on the options available, but where he could also have the greatest impact. Would helping to shape dozens of young males every year be more beneficial that whatever his other options are (doctor, researcher, NFL player)? That is only a question he can answer.
As far as timing, it might be right. I still see Tressel staying for another 15-20 years, unless his interview with the Bills went well yesterday (Just kidding). That certainly is time for CK to pay his dues and work his way up through the coaching ranks. The pay for being a doctor is good, but how many doctors make $1.5 - $2.5 million a year? Probably the same number as football coaches who make that kind of money.
Anyways, I could see him doing it. Whether he has ever considered it is something I do not know.