I think it would be great if we can get it.
and I been supporting it for years
If you take a look at other countries, it work great and is cheap too
anyways the reason why it would never happen is:
1. you talking about getting rid of many healthcare insurance company (blue cross blue shield, humana, aetna, united, etc..)
2. getting rid of many administration job ( since there only one provider many people will lose their job)
those are the two reason, why i think the single payer will never happen
people don't want to lose their profit and jobs
they going lobby hard to keep what they have