I don't think that will happen.
People put off retirement now because if they don't have a decent private pension, Social Security provides just enough money to live in the upper stratum of poverty. Anybody who thinks Universal Medicare is going to provide anything other than the minimum essential medical care is kidding themselves. A lot will depend on whether the enthusiastic socialists try to make private insurance illegal. Many other nations who have ostensible "state" health care have not been stupid enough to do this, but our local breed of socialist is pretty damn stupid.