"How employers respond to the law's pay-or-play penalties might reduce employment opportunities in low-wage industries.... The lack of final regulations on major provisions of the [ACA], including ones implementing employer penalties ... means that many employers do not yet see clearly how they might restructure their employee benefits or, in some industries, restructure their workforces in response to the new law and regulations. The employer penalty rules ... and separate nondiscrimination rules for fully insured plans could make it difficult for companies to restructure, especially in industries such as retail, food service, and hospitality, 'unless employers are willing to limit large portions of their workforces to less than 30 hours per week[.]'"