Things maybe to think abot:
How passionate is he about math?
Does he do his own practice/math experiments to cement his learning or his he just burning through multiple choice and short answer problems?
Future considerations aren't just coursework, but also about maintaining a passion if it exists.
We'll be facing a similar question, and I have no intention of getting between DS and his passion. But he doesn't have to follow the linear path schools imagine for math.
Push come to shove, find sideways material that he digs. Maybe like number theory, statistics, topology, operations research, other discrete maths, etc. I can imagine someone motivated spending a semester just exploring proofs relating to primes.
