I would create a per-capita federal refundable tax credit which is commensurate with the average cost of "comprehensive" market health coverage for an individual, but not mandate people to buy anything other than catastrophic care coverage.
If the tax credit based on comprehensive coverage was $1000/month, and catastrophic coverage cost $400/month, would someone who chooses to only have catastrophic still receive the $1000/month (giving them $600/month they could use on anything regardless of whether or not it is related to healthcare), or just receive $400/month, or receive whatever their insurance and medical costs actually are each month up to $1000/month?
If the later two it would be universal healthcare. Not sure how the first would be classified.
Dunno what you'd call that.