I don't think the positive differences would be as dramatic as some here are proposing.

It would immeditately benefit a lot of people with existing large medical bills or chronic health conditions. But this probably wouldn't be an immeditately noticeable economic boon - instead, it would take the form of these people unburying themselves from debt and building up savings.

Over the long term, I would expect more small businesses, more people starting families, and more people choosing to retire earlier. But I think it would probably take a decade or more for this change to really be felt by those not directly impacted.

In the short term, there would be a massive economic restructuring as the entire health insurance industry collapsed overnight. Literally millions of people would be out of work. In the long term, this would be a good thing - but short term, it would be a very big problem.