> Narrowing what the Federal Circuit thinks is patentable, yes. Narrowing what the Supreme Court thinks is patentable, no.
The Supreme Court rarely narrows what it thinks. They look for ways to judge each case in a way that (they can claim) is consistent with prior rulings.
The Supreme Court had never ruled on the subject matter of Mayo or Myriad before. Until they rule on something, the patents are "valid" if the PTO grants them and if the courts uphold them. In those two cases, the Supreme Court's ruling means the PTO has to stop granting a certain category of patents, and the lower courts have to stop upholding them against product developers. That means patentable subject matter got narrowed.