It's difficult to comment when I haven't seen or heard her play. Normally I'd want to hear a certain maturity of embouchure/airstream control, as without this the soprano will find that out rather quickly.
Having said that, none of us know for sure do we and having NO opportunity is awful, so why not find out. You may find that one true love appears - all well and good. Experience/appreciation of the other instruments is very much a plus as a musician too.
I think that the most valuable thing for aspiring musicians is to be surrounded by like-minded people and a depth in talent - if this becomes exhausted at school then you move to county level - and so on. Teachers too - able, with a good (broad) attitude and knowledge.
As Skeller says above about the Basset Horns, you never quite know what journey a school music department can go on if the correct staff, students and parents have a good attitude with funds available. A school I was brought into as a sax specialist went from no ensembles at all to a Big Band, Wind Band, Brass Band, Soul Band, Choirs etc - all down to the new Head of Music and the support of the Headmaster. I ended up running two full SATB sax quartets, playing some challenging stuff like the Saxtet arrangements of An American In Paris and Rhapsody in Blue - aged 13 - 16. This was almost unheard of at a non-private, regular Comprehensive school. The school had about 20-odd saxes (SATB) that it could loan the students, who generally went on to buy their own.
Amazing things can happen..