How many strong EC do you need for very selective colleges?

if he wants to walk away from music, after devoting every free waking minute over the past decade, its his choice.
I’ve never met a 15 year old who knows precisely what he WILL be ABLE to do or even WANT to do 3 years from now. kids do change their minds, ya know.
So it may be up to you to do the research, and guide him, so he doesnt make a mistake that he will later regret.