"When reviewing a potential merger, [Assistant Attorney General Bill Baer] stated that the government will look at the future of the market -- not at how the markets appear today -- and will evaluate how local companies may increasingly compete regionally or nationally. In addition, Baer noted ... [t]he 'countervailing market power' justification may not be effective moving forward.... The government will investigate to ensure that mergers are not designed simply to take advantage of higher reimbursement rates even when there is no change in care provided."