The Supreme Court has been surprising me recently.
That said, it seems almost inconceivable that it will approve any material changes to the Senate without a full constitutional amendment process. Perhaps they will allow voting to nominate Senators for the Prime Minister's consideration but even that is doubtful.
So then what?
I cannot imagine this government wants to open the Constitution (maybe I am wrong here but that's a high risk step) and so,,, Senate reform dies.
Perhaps the best we can hope for is appointments actually made on merit.