Moxie, I see the original post is a bit old, but a year or so ago, I researched college programs where a student could major in dance but also continue music as a serious hobby (minor or second major). I was looking more for jazz studies (musical), trombone, music production, and music composition opportunities, but this list might help you expand your current list. This information is based on information at university web sites, and everything should be double-checked with the schools, because it could be out of date or I could have misread the fine print! I realize there are a lot of top schools on this list--I don't necessarily think my ds could get in to some of them--but it's good to know the opportunities are there.
Dickinson College has combined music/dance major with classes taught by CPYB.
Columbia has ballet through Barnard and a lot of music opportunities, including a connection to Juilliard for the very talented.
Princeton offers certificates rather than majors, which allows for more doubling, and music and dance look very doable.
Harvard has a program with New England Conservatory. Harvard has good ballet club.
Indiana seems to have some new music minors open to Dance majors, but I have to confirm this.
At Michigan, Indiana, and NYU, ensembles are open to non-music majors.
Also, for possible double majors, look at Butler, Duke, SUNY Purchase, Southern Methodist, Goucher.
Cincinnati does not have many music minors, but double-majoring looked somewhat possible.
Harrt was also on my list, but I don't have a lot of information on this one.
My ds won't be giving up music, no matter where ballet leads him. It's just who he is.