Even in a socialist system, scarcity still exists.
The free market have an obvious mechanism and it is called profit and loss.
Private health care rations treatments based on ability to pay.
I know which rationing system I prefer - for both ethical and pragmatic reasons.
If that's the definition of universal health care, no country I know has it, because there is no country I know of that has successfully banned cosmetic surgery.
Still, take birthmark removal: it's purely cosmetic, in a sense, but it makes such a difference to peoples' quality of life psychologically that it totally should be on the NHS if you ask me.
I guess the determinant of whether or not we're actually ready to move into the next stage is whether or not technology has advanced enough to make health care cheap enough to be supported through the government. Of course on the other hand if we don't make this push we may not even have the incentive to make healthcare cheaper. So in other words, we have to create some irritation to make health care less scarce, just as we have to irritate a wound to have it heal faster. Obama's plan may be that irritation. If the plan strains the national budget then we will be more inclined to figure out how to make health care cheaper, and as a result a nonissue. I mean most other first world nations have nationalized health care so it's about time to make that push right? So that basically explains why we should move towards that direction.
So as my response relates to scarcity, the plan allocates resources better by taxing the wealthier americans more. But we can't hope to support this plan by constantly creating better allocations. Obama's plan is assuming that we're at a point where medical care is cheap enough to be supported by allocating a little more from the wealthy.
An insurance company will allocate health care based on profit, the government will (hopefully) allocate it based on need, and that's where we're aiming to go to make it a nonissue for Americans (and everyone in the world ideally).