I mentioned this when the ruling came down, but the visibility of the case makes it the perfect vehicle for labor to strike a major blow at arbitration agreements. It's going to the Supreme Court.
That said, unless Clinton is elected and gets a justice through, it will just end up 4-4 and the lower court ruling will stand. And even if she does get a justice through (or if the Senate approves Garland in the lame duck session), there's no guarantee the justice will be sufficiently pro-labor and Clinton's never been much of a supporter of the working class; there's also no guarantee Garland would land on the labor side, either.