Public support for Medicare for All is going to look much more interesting in a few years when the Medicare trust funds are running out and they have to cut costs by 15% or more, and it’s clear there’s actually a price tag on the proposal.
More broadly, by having a single payer, a reasonable Medicare For All program would in total save Americans vast amounts of money though of course as a program it would have a cost.
When this happens, voters will not like what they are being offered quite as much as they do now, when the costs are some distant abstraction; there will be a whole lot more hesitation and skepticism. And if pointing this out is a "right wing talking point" then go ahead and call me Margaret Thatcher.
I could imagine a scenario where an angry public demands the government take control of hospital finances.
Not that it's necessarily a good thing, but I could see it panning out that way.