If I were him and didn't win the NC, it's a choice of....
Go to the NFL as a JAG and coinflip at best to be on a 53 but likely a practice squad guy with a practice squad salary.... Maybe more in a perfect situation/team for him.
VS
1. Being top man on campus for another year
2. Setting more records and becoming even more part of ND history
3. Another shot at a NC
4. Another year, but with likely more talented WRs, and more matured TEs/RBs
5. Getting more free education
This year's QB class is very solid/deep. There's also a ton of QBs in the league already looking for a job bouncing around and available with more experience, and competing for backup duty. It's been a buyers market lately.
I have know clue, but if he does want to go into coaching, staying another year doesn't impact that either. Probably helps.