One problem with the politics of the public health insurance option is that roughly zero percent of the voters know what it is. Would it be go down more easily with the public if it were called “allowing people to buy in to Medicare”? It shouldn’t be impossible to compute a set of break-even premiums, adjusted for age and location, at which Medicare could provide its current level of coverage to people not currently Medicare recipients.
Or it might make more sense to create a new program – to be called “Young Medicare” or some such – that had somewhat different coverage. Even then, administering through the current Medicare bureaucracy would save having to set up an entirely new system.