The teachers here at my school seem to basically give A's assuming you show effort. The music program at my school is pretty small, and the teachers understand that music is not student's first priority.
A warning though trying to get Peabody or Julliard teachers... that is very difficult. BassDad already mentioned this. I have a friend at JHU who played piano for like 10+ years, and he couldn't get lessons with the piano teacher.
Honestly, it's very hard for me to see a teacher at a place like Peabody or Julliard taking on a student who is not going to practice 5 hours or more a day. Taking lessons from a student of the teacher, as BassDad mentioned, might be a more viable option.
All schools have ensembles for students not majoring in music, and those will not require much practice time, but allow you to keep playing, and possibly earn 1 credit worth of an A.