Personally I think if the Gov't is serious they would buy the land to enable 18/36 at Richmond (mind you there would be a crap load of earth works required to level it) and make that the next Sydney Airport, and divert the rail track to make a Richmond Airport rail station. Then move the RAAF to Dubbo (i.e. a better place than Sydney) - better quality locals there . Problem being the Lower North Shore brigade would resign - and resign instantly
Not much RAAF in Richmond to move anymore. Could be a 'joint' facility.