No they won't. Insurance companies pay the tax. They will pass the 40 percent on to the employer. Employers will drop the plan because it costs 40 percent more than its actual cost after the tax is paid. Employees will thus be forced to go with a government-approved plan with worse coverage.
Maybe part of this is to force normal folk to join a union in order to get good health benefits. You have an office of professionals used to getting good health care; maybe they need to join a union to get the same coverage that SEIU people get. The problem is, once a union is formed, the goons take over and they syphon funds from the workers. So that is not a solution, either. The only solution is to defeat this evil legislation.