That's why many proposals that scrap employer provided health insurance, give the same benefit to employers via HSAs (a pre-tax health savings account ).

In effect, instead of the employer picking the employee's health insurance the employee could go to the open market, but both the employer and employee get the same tax benefits via putting money pre-tax into a HSA which can then be used to pay for health insurance.

It would require massively increasing the maximum contributions on HSAs (currently only $6,750 for a family), since HSAs weren't originally designed to pay for your health insurance, just healthcare costs. But conceptually it is the easiest way to allow consumer choice in the health insurance market.