The key thing is not to think of musical training as necessarily leading to a ‘professional track’ and by this, I mean getting into a full time orchestra, getting into a relatively major opera company, etc and that is your career (or even more rare, as a soloist). The problem with the plan B is you get into the mindset of “If music doesn’t pan out, then I’ll do X”, rather than “to make music be in my life, I’ll be aware of other opportunities”. One of the problems with an approach of Plan A and Plan B is for example, kids going into music education because “it is a lot more solid career” when they don’t really want to teach, or it leads, for example, into the student dual degree, which takes time away from practicing and such, so when a parent says “well, you should dual degree in music performance and accounting”, they could be sacrificing the music because doing a dual degree can limit the hours available for practicing and such. It doesn’t mean that a dual degree might not be a good option, just that in the move to try and ‘have something to fall back on’, you kind of create a self fulfilling prophesy.
I think the better approach might be to think of things to be able to stay with music yet make a living, looking at what you can do if you want to stay with music and that dream job with the NY Phil doesn’t happen. One of the misnomers is somehow that most college degrees are direct job training, they aren’t, Engineering to a certain extent is, comp sci is (though to be honest, a lot of what you learn directly in comp sci often has nothing to do with real world programming jobs), but for many liberal arts positions or the generic business admin degrees, you learn most stuff on the job…and as others have said time and again, for many jobs a music major degree (or grad school admissions) will work for a music performance degree as it would for many college degrees. Even with a bachelor’s in a science field (chemistry, physics, biology), people often end up in ‘regular’, non science jobs and those won’t be worth any more than a bachelor’s in music performance (put it this way, if you get into marketing, those fields likely won’t help all that much, as an example, over a music degree). To be honest, the real fallback is to recognize that for many college degrees the value of the diploma is not direct job training, and thus first focus on music in school, and be thinking about creative ways to get into music, use music., once you graduate, and then if you find it doesn’t work, use your college degree as that…and recognize that music majors have unique skills that other majors don’t give, and take it from me, most employers know that.