No sane or decent person expects the nation to be able or liable to ensure the health of every non-citizen. No sane or decent person expects children who are citizens to be able to ensure themselves. No healthcare system can endure without enforceable borders. No decent healthcare system can endure without ensuring for the care of its dependent children.
Problem is, citizens are remaining childish and dependent much longer today than ever before. Many have lost responsible parents to State interventions and intrusions. Many are unable to gain decent employment without extensive training. Before they get that training, they cannot afford healthcare. After they go into hock to get that training, they cannot afford healthcare. Moreover, frequent re-training tends to be necessary. Making employers pay for such healthcare puts the nation at a competitive disadvantage against nations that do not put such imposition on their business employers.
This state of affairs tends to make individuals too non-independent to be able to secure decent health insurance at a reasonable rate. Rather, the people become more like dependent stock, to be debt enslaved and farmed by oligarchs and their insurance companies.
In a nutshell, this is what Trump is called upon to try to fix. Or to get the Feds out of the way, so States and State compacts can fix.
Musings regarding Krauthammer and Single Payer (I am not here trying to give an objective interpretation of the Constitution; I am only musing about practicalities):
It is probably too late to put toothpaste back in the tube. Fed money to buy health care will likely be ruled Constitutional, as a "tax."
If so (again, "if" -- and, note: Trump will be appointing judges and justices, and seems to be on record for favoring something akin to single payer or the Australian system), then:
To be a single and decent society, a nation should have a single and unifying safety net, sufficient to ensure human decency even when an individual citizen has become without a job, family, support, or hope. The net should not, however, become a hammock, nor should it encourage citizens to become sloth-like.
To compete internationally, a nation's private employers should be freed from the onus of needing to provide health insurance for their employees.
To remain a decentralized federal republic, the extent of central regulation on domestic matters, such as health care, needs to be minimalized, without sacrificing decency.
HOW might that be done, consistent with our Constitution?
Eliminate most obligations to insure illegals and invaders.
Set up parallel competition via a private system, in which insurers can insure across State borders, and in which policies are made portable across borders.
Allow States to join in regional/area co-operative ventures for ensuring State employees, citizens, and residents.
Allow States/Areas to set limits on fees and costs by making reference to private insurance costs and rates.
Provide a tax credit for every citizen (or for every filer who reports some minimum net income), to be usable only for purchasing health insurance.
Call the health insurance provision a "tax" on the productive health of every citizen.
It will be interesting to follow convolutions and evolutions on this issue of health care, as proceedings unfold ....