The assumption here is that the service can be provided within a price point that doesn’t kill the demand.

That’s not the assumption at all.

Health Insurances companies would spent time and resources on actually denying care, even to those who would or could pay the premiums. That’s exactly the debate over ‘pre-existing’ conditions.

There is obviously a large, unfulfilled demand for medical services in the U.S. What is missing is the financial resources among the people demanding services to pay “what the market will bear”

Part of Obamacare, that was not part of Romneycare, is the Medical Loss Ratio: a specific regulation requiring Health Insurers spend the majority of their premium revenues on actual health care and not on administrative costs; which administrative costs were mainly directed to either executive salaries or determining care denial.

or perhaps a cheap enough training process for providers that the supply of providers can be expanded to meet the unfulfilled demand.

Prior to Obamacare, health insurers spent dime on specifically determining who could or could not have insurance, regardless of the ability of people to pay the premium. Or, put another way, they were actually and actively saying a clear NO to the demand.