There is a significant lag time on Federal litigation. District Court litigation will likely not be complete until towards the end of 2018 or early 2019. Court of Appeals litigation will likely not be complete until late spring or early summer of 2019. Meaning that this case would not even get to the Supreme Court until late summer of 2019, for consideration in the October 2019 term. Who knows what the Supreme Court might look like by then.
Iowa is hoping that Trump gets a new Justice in place of Kennedy and/or perhaps RBG.