I am not sure where did you read that the PNHP does not call for a single payer system. The opening page of of their website talks about it. Also here is an excerpt from the Physicians proposal intro: "The Physicians’ Proposal for National Health Insurance establishes the vision and principles of a single-payer health system for the United States. The document was composed by a distinguished group of physician leaders*, and secured the endorsement of 8,000 physicians by the time of its publication in the August 13, 2003 JAMA." (http://www.pnhp.org/single_payer_resources/physicians_proposal_intro.php)
This may not constitute the majority of the physicians of this country, but at least a large chunk that feels something needs to be done and possibly single payer system is the best way. Till date I have not met a single doctor who is happy with the insurance companies and HMOs. They have to accept whatever negotiated rates these companies set with them. Then why not have a single such company and cut all the other red tape?

Medicare being an offshoot of the social security system is under a huge financial burden and we all know about it. Social Security needs to be fixed anyway, but Medicare as a health care management system has been largely successful in providing care to its target group so far. 
I agree, that when we retire, things may be even worse - no Medicare and no health insurance company or HMO willing to provide us with the insurance we would need. Hence the system needs to be fixed, and the solution does not likely to be the current way of profit motivated HMO type system.

Health care should be a right. It cannot be subjected to the capitalist market system - since when a patient needs care - he just needs it. He has no other option. Health care is not a consumer commodity that one can possibly live without. But that's what the current system is making us do - to choose between a index finger or a ring finger ( as the film shows) or to make a trip to India or Cuba for "Medical Tourism". 

I would very much like our community's feedback on this issue and welcome your suggestion to have an  open discussion forum.