I agree with much of what Shure is saying here: Medicare for All certainly does have "popular support," but it's kind of a passive one. People who have insurance right now and are OK with it don't want to risk everything for creating a system they aren't sure is going to work. This is clear when even within the labor movement, some trade unions oppose Medicare for All outright. That is surely a sign that this could not be passed anytime in the future.

But, as Shure says, just getting this debate in front of the public is crucial. Everybody knows, either intuitively or explicitly, how crazy the American healthcare system can be (from pharmaceuticals to ridiculous health insurance options). But it does work, in some sense of the matter, especially when we compare healthcare to simply 50 years ago.

Elizabeth Rosenthal's book, An American Sickness, is a deep-dive into the history and current state of American healthcare. If this topic intrests you, I did a short review of the high-level concepts in the book: https://inquiringreader.org/texts/2021-01-09-an-american-sickness/. It's well-worth a read if this topic gets you riled up.