This!^^
All kids are different and he has some time for his plans to evolve. There is no right path or thought process. But having NEC, Curtis, Blair et al, as one plan and then pivoting to a completely different degree with a good orchestra available seems like it might be tough. It almost sounds like he is going for broke at the tender age of 17 or so.
Just a suggestion to consider some slightly less selective music programs to allow for choices. It is hard to know where his thoughts lie a year from now. Young musicians grow so much over the course of the application and audition season.