Not sure what the potential load would be like for QANTAS if it were to extend it's JNB flight to Cape Town or Durban. In my days in SIA the SIN - JNB sector was usually pretty full but we then, (with a fresh crew), operated a shuttle to either Cape Town or Durban and the loads barely warranted a B737.
Obviously QF have a different catchment area and may get a better load factor to Cape Town etc. but it may pay them to have an agreement with SAA and save on crew, aircraft hours etc.
Just my thoughts.
