What If We Can’t Get Medicare For All?

Like most lefties, I would like the United States to adopt true universal health care. This has been my position for, oh, 30 or 40 years. However, I also accept the reality that this will never happen in one grand swoop. That’s why I was—and am—a big supporter of Obamacare, warts and all.
So if I were president and had to propose health care reform that actually had some chance of passing, what would it be? I’d go with a two-prong approach:

Lower the Medicare age to 55
Add Medicare as a public option to Obamacare.

Employers could keep their current private-sector plans if they wanted to, or they could enroll their employees in Medicare. The federal government would make Medicare available at its cost.
There are details, of course. Perhaps Medicare reimbursement rates would have to go up. Employers might need to offer Medigap coverage. Etc. But this would be a big step forward.