Politically, the only path I see is calling this "Medicaid reform" because Medicare is a third rail. The basic gist is that Medicaid gets converted to a VA-type model with no profit incentive and no insurance company middlemen.
The federal govt offers states the option to accept block grants for Medicaid AND Medicare (and potentially VA). States like CA gradually divert funding to this new model and make it available to all residents, unconditionally. $20 copay for your basic health needs. No questions asked. No pre-auths.
Over a 10 year period, the state stands up medical clinics, hospitals, labs, and imaging centers. They hire docs, nurses, NPs, and whoever they need. The state provides 24/7 telehealth by licensed PHYSICIANS, moonlighting/working from home, because triaging is critical for resource management.
There's a wait list in certain areas for certain things. Some name brand drugs aren't available. Some new treatments are not available. There are no specialists available for certain rare conditions. There are no disability payments available from this program. This is not a perfect world.
Eventually, Medicare recipients will find it more convenient and economical to use the new services vs Medicare. Medicare is eventually phased out. That's the hope the idea hinges on...