From there, insurance would likely break down into high cost / high coverage, mid cost / mid coverage, low cost / legally mandated minimum coverage.
The poor would end up with the low cost / minimum coverage plans as cost would likely end up being the main motivating factor. Given that 6-in-10 Americans can not afford an unexpected $500 bill (https://www.cbs19news.com/story/34248451/6-in-10-americans-d...), this would likely be the coverage level chosen by about half of Americans. These policies would be affordable, but I expect the deductibles and co-pays would be high enough to make it prohibitively expensive for policy holders to actually get much utility from them.
The other half would end up with the better plans, unless they were more comfortable with risk and elected for the cheaper plans. Their lot is probably pretty similar to today.
Americans can afford a $500 expense just fine. The median American household has ~$1000/month left over after all ordinary living expenses, per the US Bureau of Labor and Statistics.
I think they're drawing on this series of studies: https://www.bankrate.com/banking/savings/survey-how-american...
Start from the well-sourced fact that median American households have ~$1000 per month to spend without sacrificing anything, and work from there. This can't be true at the same time all of those breathless headlines about broke Americans is also true. Without fail, if you dig into the details, the headlines are grossly misleading. The percentage of Americans that truly have no capacity to deal with significant unplanned expenses -- per Federal Reserve studies -- is 10-15%. A not inconsiderable number of people but far less than implied by the clickbait.
Average Americans have extraordinary amounts of discretionary income compared to almost anywhere else in the world. Americans both have a low savings rate and they have large amounts of money available to save.