Servo Controlled Potentiometer using Rotary Position Sensor
Yes, that should work fine.  The rotary position sensor you have pictured is made for servos like this; if you open the servo you will find such a pot used for position feedback.

One concern is crosstalk.  The PWM signal is in the audio range, so any signal that bleeds through will be audible.  This can be engineered around.  I suggest separate power supplies for the position controls and the audio.  In particular, do not allow the ground signal to be shared between the position and audio circuits.