Nope. Hand-in-hand with the individual mandate, a broader Medicare-as-public-option would end up having a lot of younger buyers. Plus, a lot of employers, especially smaller ones, would see Medicare as an attractive option as well, which will further improve risk pooling.

It doesn't have to be. Some plans push for a complete replacement of all private insurance. I see no reason for that to be the case. If you want to pay for expensive insurance that, say, has broader coverage, or more in-network hospitals, or other perks, you should be able to go for it. And such plans should be available for employers to buy as a perk they can offer to entice talent.

None of that is in conflict with a public option available to everyone else. This is literally what Obamacare was initially designed to look like. And there have been several Medicate expansion proposals that broadly match the scenario I outlined proposed by several Dems.