Me thinks Trump will fix things with executive orders moving forward as Supreme Court rarely reverses En Banc decisions... so yes they could but doubt it will go anywhere if they do.
Based upon "The Plan" they were intending to allow the companies to start retaining capital anyway. This ruling gives them cover. "Why would we appeal, if this was what we planned to do anyway. We are simply being directed to do it sooner than we planned. [Smiling] Don't blame us ... blame the judges of the 5th circuit."