Not knowing the specific situation at your district and community it's hard to say. My suggestions are: look into community youth orchestras, consider picking up another instrument in the school program.
Our district's orchestra program also starts out assuming students have no instrument background. This is not true for many, many students. So a lot of students choose another instrument to learn in the school program.
After two years of mandatory program, our schools will offer more options for those who are ahead. In high school there are a few levels of orchestra and for the advanced levels all students are required to take private lessons. The top level is actually quite competitive.
That said, we are facing a tough situation ahead as well: my DD9 is a very advanced musician and has played in very competitive orchestras (most members are strong musicians in high school and middle school) for a while. And she already learns two instruments and really doesn't have a third in mind that she wants to learn. She has begged me multiple times to talk with her school and let her be exempt from school instrument program when it starts in 5th grade. I'm going to make a valiant effort--though have no idea what outcome to expect.
DS picked a third instrument when the school music program started, bored silly in the program for two years (mandatory), and was so happy when finally he didn't need to do it anymore. He is a very strong musician and all the training is now done outside of school (local university, youth orchestras operated by professional orchestras, private lessons, etc).
