It won’t change, too much money is being made and they can buy all our politicians, all of them
Also: if the gov't buys as a "single buyer" it has a lot of purchasing/bargaining power. The system in the US is (lobbied) to not give the govt any power, and put it all in the hands of the market (insurances, etc).
It's be said many times: never let a capitalist come near your healthcare system.