I don't know how to answer that. I think the system is pretty inefficient in a variety of ways. If you universalized Medicare, eliminating insurance entirely, you'd get costs somewhere in between Medicare's current admin overhead and the overhead of private insurance (you mechanically would not get Medicare's current overhead, because the majority of your customers would have much lower claims than Medicare's all-seniors patients do, and overhead is a ratio).

But the largest inefficiencies are all on the providers side. We simply pay practitioners too much, enforce artificial scarcity of practitioners, and prescribe too many services.

So if we're talking about "The American System" as a whole --- which is what the thread is about --- it behooves us first to consider the question "how much better would things be if we simply zeroed this category of expense out". The answer is, to a first approximation, we would get a 6.5% price break. I would not drive even a couple blocks out of my way to get a 6.5% price break on a pack of chicken breasts.