John Goodman runs some numbers and shows that Medicare is unsustainable.
There are two important consequences.
1) If we move towards any form of government-run universal health care (such as the proposed "Medicare for all"), the problem will become quickly worse.
2) The government will eventually have to cut health care spending. In other countries, this has taken the form of draconian rationing (e.g., "no dialysis if you're over a certain age"). Basically, the government determines what their citizens' lives are worth.
That's why we need to adopt free market health care reforms as quickly as possible, where the usual market mechanisms can lower costs while preserving quality. We don't have much time to act. All we need is the political will.