In terms of no easy privatisations remaining, look at the railways - true privatisation is virtually impossible. All they can do is break them up and spin off parts into subsidised franchises or new government bureaucracies, only fully selling a few pieces like freight operators. With that arrangement comes all sorts of new inefficiencies and boundaries that need to be negotiated, industry regulatory bodies, clearing houses, more paperwork, more management, and legal fees.
Similar story with Australia Post and Centrelink, it will probably actually cost them money to privatise because of the complex nature of the services they deliver.
Australia Post will likely need big hunks of cash to continue to deliver any kind of universal service obligations - especially to rural and remote areas. I read in Canada recently that they have decided not to deliver mail to large parts of the country and instead you have to go to the post office and pick it up yourself. I can't see them going for that here - I think the Nationals would cry blue murder (and Hockey's already shown how frightened they are of them) so it will probably have to be heavily subsidised.
Same thing with Centrelink. The insurance industry has been crying out since Howard to get their hands on it - but even Howard baulked at that because he knew it was going to cost them a fortune to pay out all those public servants. In addition it will probably cost them lots of money to continue to deliver the services because it will be cost plus margins from therein - so we're look at a privatisation purely for ideological reasons but I still think they'll go through with it because it's a way to get rid of public servants en masse.