Yes. There is no appellate court above the Supreme Court. The only way things could change now is if Congress/President passed a new law, and I don’t think API copyrights are near the top of the list.
That is true.
> The only way things could change now is if Congress/President passed a new law
That isn't true at all; the Supreme Court is free to change the law by itself. Someone could sue over the same question and get a different result overruling this one.
https://en.wikipedia.org/wiki/List_of_overruled_United_State...