Doctors would generally be better off in a free-at-the-point-of-use service.

Maybe the ones who are in it to make a killing, rather than make a living, might lose out - but what kind of doctor would it be who was in it to make a killing?

The people who would stand to lose would be some sections of the insurance business (others might stand to gain in fact), and the impression I have is that this is the source of massive propaganda aimed at persuading the public and the medical profession that they have something to fear in changes which would provide free health care for all.

The British National Health Service is a product of a particular time in a particular society, in a relatively centralised country. I suspect that for the USA the German model might be more likely to suit. Here is a short overview of Health Care in Germany Germany, which of course is a Federal Republic, has a system that is insurance based, with, I understand, a major part played by church linked medical services. All things that should translate readily enough to the USA.