The EPA can make the most reasonable rule possible, based on available facts, expertise, and public consultation, and have it overturned by a handful of judicial partisans on behalf of people willing to throw money at litigation. I think we'll see a huge increase in forum shopping and demands for injunctive relief designed to grind any kind of regulatory action on any topic to a halt. In many cases litigants will bring cases without any expectation or intention of succeeding on the merits, but rather with the sole goal of tying things up in court for the duration of an electoral cycle.
From the mouth of John Roberts himself: "courts must exercise their independent judgment in deciding whether an agency has acted within its statutory authority." This is not going to end well.
