Insurance companies are already making money from Medicare, and not just on Medicare Select. The Feds pay the bills, but there are 5 regional contracts under which private insurance companies actually administer Medicare.

If you work for a large company it’s pretty much the same thing. Your employer brings a risk pool and then a private insurance company like Cigna quotes for how much it takes to “fill” it while taking their vig.

I would expect the same under M4A: 5 really big insurance companies would continue to cost-plus bill the Feds, and then maybe there would still be a few re-insurance companies to cover stuff M4A doesn’t cover.