Obama wanted to make a 'public option' part of Obamacare. Under this option, we'd find the average cost per patient of Medicare and allow someone to voluntarily 'buy in'.
To me, this was the fairest idea. If Medicare could do a better job, people would migrate to it and private insurance would lose them. If Medicare sucked, people would voluntarily leave it and go back to private, commercial, for-profit insurance. No public expense. Freedom of choice. Free market competition! Just what the Republicans said they wanted! So why did they kill it? (Because Medicare didn't provide massive political sponsorship, that's why. That's why the Public Option was cheaper!)
I'm not sure if the 'Medicare For All' proposal is really just a reinstatement of the Pubic Option or a mandatory moving of everyone to Medicare. It could be either one.
Did you know Medicare has a much higher customer satisfaction rating than commercial insurance?