Underemployed (part time, whatever) or sort-of-poor and not disabled people in their 50s are a major segment who can't pay the real cost of their medical care, though. Or, people with lifelong expensive illnesses in the 0-64 age range (who are often making a lot less money than median, too, due to their medical conditions.)
Those in their 50's should have had some cash built up from earlier savings, but they spent it all on premiums instead of building up a hedge. Lifelong illnesses are something that we should just acknowledge as bad for insurance and deal with otherwise. Insurance should be for events and not continuous medical conditions.
We have not dealt with the price of medical care in a sane manner. I don't think the political will exists to break the current insurance scheme while at the same time not overreaching with government.
Being old is just a series of increasingly severe health events till one of them kills you.
Even people with dementia don't typically last longer then 10 years (which is the sort of time frame you're looking at for people who recover from cancer to stop racking up bills).
The concept of insurance we use for healthcare is broken.
You act as if an expansion of Medicare to cover prescription drugs was an alternative to the more recent reforms, rather something that already happened prior to them and did not, as you suggest, address the problem that the more recent reforms were aimed at.
