…my first reaction would be disbelief. Since third grade, I have been certain that performing music will be a part of my life, if only singing in the shower. Losing that would be terrifying, and require an overhaul of my life: every school I chose to apply to this year needed a music program. If a school lacked some way for me to pursue singing, I did not even consider applying to it. I imagine that listening to and critiquing music would become a much larger part of my life, as I would still want to interact with it in some form.
I would also look for schools with writing and mathematics, rather than music and mathematics. One of the reasons I love music so much is the fact that it is communication, and my main method of non-musical communication is writing. I would either settle into poetry or creative writing, or write in both, as I have been. The main difference would be that writing would be the core part of my life, rather than music.
After some time, I expect that I would write poetry to perform, and maybe even write songs for other people to perform. Writing without performing is particularly good for me when I am healing, because I feel relatively safe, but performing is something I love to do. Music or no, I would perform.