But only if there is lots of competion and a lack of a powerful wholesale market.
One of things we tend to ignore when talking about our screwed up system of health insurance (and the lack thereof) in the US is the effect that wholesale insurance has had on the retail market. Consider if medicare, medicaid and company programs were all to dissapear tomorrow. Would you see a vast swelling of the ranks of the uninsured? I doubt it, simply because without the wholesale markets insurers would have to compete for people on an individual basis. All those middle and even lower middle class people now covered by some form of company or government insurance would probably still end up insured. I wouldn't be suprised if health insurance became cheaper in this case, as no longer would there be the phenomenon of people in various jobs getting the "wholesale" price through their employer and other people paying a much higher "retail" price. On the other hand, the poor and those with existing conditions would still be SOL.
Now imagine if there was no insurance. Everyone has to pay their doctors directly. I think in many, many situations, things would be much cheaper. Drug companies would lower to price in order to be able to sell the drugs. Doctors would make visits cheap enough that average people could pay. On the other hand, this would create a system where the best doctors would charge more, and the poor might recieve more medical care but of lower quality. Of course, in reality this would lead to the recreation of insurance companies, but anyway...
The problem in the US is that we've managed to create the worst of all worlds in a way (well, not really, because if you have money you can get great care in the US). We've created a mix of wholesale and retail where the wholesale market is the larger one, and therefore retail is much, much more expensive. We've also created a system where costs are hidden from most consumers, so the costs of drugs and treatments are inflated since they are paid by insurance.
In a system of government health care, there are other issues. Everyone still pays, they just pay with taxes. Every citizen is covered, but nocitizens and such may suffer for it. It's been argued that the incentive to create expensive new treatments goes down.
Ultimately I think the US will go onto a system of government run health insurance/health care, but there will be issues with this. There is no perfect health care system, and there's no free lunch either. When we discuss this, we should acknowledge that the free market does have distinct advantages, and we don't have a free market in any real sense - medicare/medicaid is a huge government insurance program. Basically we'll all be going on medicare/medicaid if we go to government insurance. Who says the government won't screw over some people as well? That said, our current system is very seriously flawed and needs to change in some way.