Unless you SERIOUSLY believe that the TNI-AU will be a serious threat in the next 30 years the only reason to have state of the art fighter is to keep up with the USAF
Well the Indonesians have publicly stated their ambition for a 10 squadron fighter fleet- 180-200 Sukhois. Whether this is obtainable or not is debatable.
The ability of the RAAF to maintain a technological and training edge over a modernized TNI-AU, makes sense, as it fits a number of other possible regional scenarios.