Should the US adopt a single-payer health care system?

[Deus Naturae]

A public option and ACA-style markets with a mandate along with the repeal of tax benefits for company insurance would probably work better with less effort.

As awesome as the end result of single-payer would be, it would be a nightmare to implement.

We already have single-payer in the form of Medicare and Medicaid, but politicians in both parties restrict access so only 1/3 of the population receive the benefits. Republicans are terrified of the political implications derived from creating single-payer insurance for catastrophic medicine, though, it would be a huge boon to the economy. Democrats are terrified of the political fallout and ideological compromise associated with swapping pork-dispensaries for entitlements that actually work.

I heard of such a scheme in the Atlantic but what would be catastrophic and when would end of life termination of care be determined or how?

I'm guessing that anything short of catastrophic care could then be taken care of in Walmart or Walgreens or something like that?

Doctor's offices are also a thing...