The IRS says
What are the consequences to the employer if the employer does not establish a health insurance plan for its own employees, but reimburses those employees for premiums they pay for health insurance (either through a qualified health plan in the Marketplace or outside the Marketplace)?,
and answers: You are big trouble, because that counts as an improper insurance plan, so you pay a fine of $100/day per employee. That may or may not be a reasonable interpretation of the statute, but it seems to me unimportant. What the IRS has said is that an employer can't cancel its insurance plan and give each employee $5,000 they must use for an exchange plan. It does not say that the employer can't cancel its insurance plan and give each employee a $5000 raise to compensate. That's what an employer should do anyway, since it has no incentive to make the employee spend the money on health insurance. The only thing that could matter (and maybe it does) would be if employer contributions to employee-bought health insurance are exempt from income tax for the employee. Then, this ruling does cut out the tax benefit.
(hat tip: TaxProf)