I have always liked the slow hybrid approach of adding to Medicare the lowest and highest cost folks...lowest to Medicare..this 55-64 and highest to the world of insurance. This would make ACA cheaper and cover the most expensive on single payer. Then keep adding. The other piece is to crowd out for profit insurance and return the the real Blue Cross as a not for profit, and maybe 1-2 others just to be fair. Of course the public option is similar.