Jay Ackroyd laughs when I state that there is serious path dependency issues on transitioning the US health finance and health care providing systems from the current set of kludges that are based on heavy but hidden governmental involvement in both for most working age adults, and then single payer systems for the elderly, the disabled and the poor.
He thinks that path dependency can be waived away by changing the eligibility age for Medicare.
The US has a single payer system in place already. Just change the Medicare eligibility age. Set premiums. Compete!
If my memory serves me correctly, there was a recent proposal to do just that and it failed.