Kaiser currently participates with Medicare as a Medicare Advantage provider. My understanding is that Bernie's Medicare for All eliminates Medicare Advantage programs, but I'm having a hard time finding anything definitive on that. Got links?
If that is true, I and a whole bunch of people are going to be against that because we actually like our "insurer" because they coordinate our care. I have Kaiser coverage and I am very happy with their care. While I'm sure that sentiment is not universal among their clients, given that kaiser is often a choice people make, I presume it is common.
Medicare Advantage is getting more popular. It's going to be a big deal if it goes away and a whole bunch of people are not going to support a candidate that will take away their current system that they like.