A comprehensive assessment should identify that your son has an exceptional talent in music, which might qualify him for a program for the musically talented. If no such program exists within his school, he can nevertheless receive services that build on his strengths in music.
A talent specialist or the school's gifted-and-talented program coordinator should be included in the development of his IEP. Exceptional talents or abilities compensate for disabilities in another area. Building on your child's strengths helps to ensure his interest in education and to motivate him for advanced study. Children such as your son may be "dually-identified" by the school; that is, they may receive services both for their disability and for their talents.
On a personal note, I have a relative who has been legally blind since birth. He is now a professor of linguistics at a major research university. He holds a doctorate and has lived and worked all over the world. With the appropriate support, the sky can be the limit for your son.