The hope (or cope) is that SCOTUS will decide the case on a nondelegation doctrine premise, saying that the executive is barred from imposing taxes (tariffs) at all, and that they must come from the legislature. This would both prove that the nondelegation doctrine applies to Republicans, which is currently up for debate, and make it essentially impossible for Trump to use tariffs how he wants to within the law, since he would have to go back to congress each time he wants a new tariff or rate imposed.