If Medicare is defined contribution, then it's like the government throws up it's hands, gives people some money, and it's up to them to get health care.
As costs continue to escalate, the government is fine, they continue to pay that amount, but the people have to pay more and more out of pocket.
You need to address the ever increasing cost of health care.
I agree, having employers pay for health insurance doesn't make a lot of sense, but again, the individuals will then be stuck with ever increasing costs. Now, employers are motivated to fix this problem.
And employers will quit paying for health care, fine, but they probably won't direct that amount towards higher wages so the employee can afford it. That could just turn into a big gift for big employers.
Better to have a tax like social security. An employee portion and an employer portion, or if you're self employed you have to pay both. Medicare for all.
You could still have health insurance companies administer it. Like with Medicare part D for prescriptions, and I think most people have a Medicare Plus insurance policy.
Have copays to encourage people not to over-use.
Take programs that work, like the Mayo Clinic or Cleveland Clinic that have recommendations for which treatments are effective and cost effective. If you say "government bureaucrats" enough people will be fearful, but if you say "doctors based on data to show what really works", maybe it will make more sense. "Death panels" is a another good term if you want people to be fearful.