I see this as a different issue - rampant cheating by, for example, the Democrat machines in Phlly and Detroit. Not the unfairness of the rules themselves as in Bush v. Gore, but rather a failure of the State legislatures of PA and MI to (ultimately) step in an apply the only Constitutional remedy (appointing a slate of electors to the EC). Since they didn't do that, it's a "political question." And then again, I don't think SCOTUS wants another Bush v. Gore and are looking for a way to punt.
Like I said, I hope I'm wrong.
My question is if they do nothing than does that change the 270 majority if those electoral votes are not in?