We will never lose SS or Medicare. When was the last time a major government program like that was cut? It won't happen, no matter what the tea party believes. They'll never have a large enough majority to enable it, and no President would be stupid enough to be the one that took all medicare away from the seniors or removed their SS checks.
1996, Aid to Dependant Families and Children
That mainly affected people who were so poor that they didn't have very much political clout at all for such a decent sized group of people. It was also easier to scapegoat welfare recipients than it is to scapegoat retirees.
When some politician makes a serious run at cutting SS you'll see even sterner opposition.. since getting rid of it would be taking from everyone.
Which is why the destruction of SS/Medicare will come in two phases. First they'll make both programs "means-tested", essentially turning them from universal programs to welfare. Once they are seen as "welfare programs", it'll be easier to get rid of them.
