Hm, with regards to the difficulty of scaling these systems specifically and really the whole topic at hand more generally I don't know that there is sufficient domain specific data to justify a viewpoint either way. I mean how many examples of scaling a national healthcare system (public, private, or otherwise) to support 300+ million people do we have? Literally three, right? The US, China, and India. Each of which has such significantly different circumstances that comparing them is less apples to oranges than it is apples to giraffes to glaciers. That being the case I feel like it's only reasonable to draw upon non-domain specific data wherein so far as I'm aware and in my experience we see a pattern of scaling existing systems being simpler than originating new ones.