If the jobs you describe are necessary, then they will continue. If they are not, they might go away. That's how things work.
We've had a long time to find these inefficiencies you describe, and yet all they've done is multiply. Cutting rates means leaving less room for inefficiencies, and is the most certain precursor to eliminating them that I know of.
I seriously doubt that any proposal would pass that results in such a conclusion. The point the article is making is that the proposals need to consider the facts that result in that conclusion (ie, current Medicare/aid rates cannot support the current industy), and need to offer proposals to counter act such a conclusion. Any proposal that doesn't is not a proposal, but a platitude.
Proposing too many details before a candidate is even elected would be foolish. Any particular detail can be distracting from the overall goal.
I think the point that you are missing in the article is that for any company offering medical services, Medicare/aid is subsidized by other revenue. That is, from the companies perspective, it is offered at a loss. If that subsidization goes away, the company can no longer afford to offer that service. The economic impact of such an event would be massive, and a serious proposal requires far more detail than hand-waving.
Healthcare is also the fastest growing employment sector.
There are huge inefficiencies in the US healthcare system. We pay more to provide equivalent service as other first world countries.
However, switching to a single-payer system with a snap of one's fingers will not solve those inefficiencies, and will create massive upheaval in just about every Americans life, and our economy in general.
The article is pointing out that if the government sets prices at which all companies decide they cannot profitably render services, 20% of our economy and 16 million jobs just vanished. No candidate has addressed this issue.