How far does training take you?

I have three kids swimming. Two girls (8 & 10) and a son 12. All the kids started together (private lessons) about three years ago. Today they are involved in age-group swimming. The girls are seeing great results (best/fourth in our country), ds is still busy "catching-up". He is incredibly dedicated and ambitious, his dream being to come home with medals... He does enjoy swimming...but, we can turn it any way we want, he is after measurable performance! Ds is good, and has come a long way. Still, I am wondering whether he will ever excel... He is athletically built and will likely be tall. These past months he has trained five times per week (2h), and will step it up to 6/7 times per week in the fall. I am wondering whether this "will do", or whether we should gently steer ds towards a sport where he can truly succeed (by his standards!!). I don't know a thing about swimming, so am in no position to judge this situation. Most of all, I am not a "pool-mom", and my only concern is, that my sun might be chasing a shadow.... Thank you for any insights!