Medicare costs aren't only question of end-of-life care. The costs of Medicare have skyrocketed in large part because the reimbursement rates are controlled by the House of Representatives and the members want to do well for their constituents.
One of the most interesting battles in the health care reform debate has been between the branches of government rather than between the parties. Obama wanted to move the reimbursement rate setting process out of the legislative branch. The House told him there was no chance of that.
End of life care issues are important questions but they are HARD questions which don't admit of easy or beurocratic answers. This is in part because metrics like QALY break down for the elderly since you don't have any valid expectation of the statistics meaning anything in relation to a specific case (and so tend to punish those who stay healthier longer). Basically if a 10 year old has Leukemia you have a pretty good idea what the longevity is like with treatment. If an 85-year-old has a heart attack, you have no idea because your standard deviation takes you beyond your average.
Everyone knows that some form of rationing is necessary. The question is what rationing system is best, not what is necessary. Personally, I think that many elements of Obama's plan go the wrong way (I would rather see a lifetime limit in costs rather than a QALY approach).