Royal Sydney is so good that they are going to completely renovate it.
Not entirely sure the standard of the practice facility has much bearing on the rating of courses. Conditioning has some relevance. The Australian is great if your idea of great is a difficult USA model course with lakes and unusual imported bunker sand. Not my cup of tea, each to their own I guess.
Royal Sydney are renovating because every green needs to be replaced due to infestations of Poa that have destroyed the quality of the surfaces. Given that they've decided to take a wider view of some other potential changes.