Realistically, no one is quitting unless they are retiring. There can be no "medical flight" with 1000's of doctors fleeing the states. Every other first world country is single payer as well.
The easiest way to model it would be take the average, adjusted in dollars, in all these other markets and determine a "market rate" for each procedure. It will have some excepetions, but that would work for the vast majority of procedures.