If they wanted Medicare for All, they could have proposed that under Obama. But it isn’t Medicare for All, which could be about a two page bill, its a 3000 page bill followed by 60,000 pages of regulations, followed by hundreds of volumes more.
How about this: lower the age for Medicare to 59, and otherwise leave it alone. That lowers the cost of private insurance for everyone else.
Just make it so that if you take early retirement, you also pick up Medicare. That way the Medicare program will get Part B payment to Gov 3 years earlier.