How could I control my servos wirelessly using potentiometers in the classic servo-knob format?
By having some sort of radio with a transmitter on one end and a receiver on the other end. There are several different way, bluetooth, WiFi, 433. There are innumerable examples on the internet of communicating wireless between two arduinos.
You need two Arduinos - one for the transmitter and another for the receiver. The NRF24 2.4GHz transceivers are cheap and easy to use.