Two things actually would make it more affordable than what we have right now.
A. Doctors wouldn't have an incentive to do excessive, and sometimes pointless treatments to make more money, as if implemented right, it will be salary pay for doctors, reducing the over all cost significantly.
B. A higher focus on preventive healthcare would drastically reduce the cost of the system.
Would it be perfect? No, but it would be a substantial improvement over what we right now in the area of cost considering what insurance companies will do to gain profit, and a system that incentives doctors to do excessive treatments that waste money without improving prospects for patients.
Yes on A. no on B.
Heard of some high end plans that tried this. DIdn't work. You end up spending a lot on tests the return negative results.