Perhaps predictibly, someone showed up in the comments to my post on Medicare and Social Security to argue that liberal analysts have very serious plans to cut Medicare's costs, which is why we need universal coverage, so that we can implement those very serious plans.
I hear this argument quite often, and it's gibberish in a prom dress. Any cost savings you want to wring out of Medicare can be wrung out of Medicare right now: the program is large and powerful enough, and costly enough, that they are worth doing without adding a single new person to the mix. Conversely, if there is some political or institutional barrier which is preventing you from controlling Medicare cost inflation, than that barrier probably is not going away merely because the program covers more people. Indeed, to the extent that seniors themselves are the people blocking change (as they often are), adding more users makes it harder, not easier, to get things done.
I suppose there's some possible argument that only with universal health care can we prevent providers and consumers from realizing there's an alternative they prefer to the status quo . . . but that implies a Canadian style system that outlaws private care, which is not what anyone's proposing, not what anyone's going to get out of the American political system if they do propose it, and not just a little bit disturbingly totalitarian.
Otherwise, people who want to reform Medicare to make it more cost effective should go ahead and propose the changes to Medicare they can get passed. I am not going to buy a pig in a poke on the slim chance that the pig might be able to get me 20% off an echocardiogram.