Think UK.
"People living in Britain can obtain private insurance, and about 10 percent of them do. About one-third of people with private insurance purchase it with their own money, while the rest receive it as a benefit of employment. Many of the big multinationals provide such insurance, either to all their employees or to senior executives. It’s considered a plum perk for everyone, and most expats coming to work in the UK consider it an essential benefit."
The UK doesn't tolerate a 100% single-payer system. Neither does Germany. The US will? I think Zeke Emanuel is nuts here. (Particularly after the VA scandal!) That's not to say that large corporations that hire large numbers of unskilled workers won't dump those workers onto Obamacare exchanges. But for skilled workers that companies want/need to attract -- private health insurance will still be there.