On another thread your son is a rising 8th grader doing serious sports, whose coach wants freshmen to bring 30-60 schools to receive films of their sports performance.
I would say that combining serious sports and serious music is nearly impossible, and even more so in the context of a challenging private school.
My kids attended mediocre public schools or even homeschooled briefly with classes online. Music in school programs is rarely sufficient for good training but can have nice social benefits. Only one of my kids is in music and their significant music activities were outside of school. If you are concerned this early about admissions, music got that kid into a top university.
Your son is young. It is a hard balance for parents between letting things happen and providing opportunities. Good luck!