Qantas axed its 5 stop Sydney-Singapore-Calcutta-Karachi-Cairo-Rome-London 707 service when improved technology (747-200B) allowed for the route to be flown in only two stops, and consumers adopted that as the norm.
Qantas axed its 2 stop Sydney-Singapore-Bahrain-London 747-200B service when improved technology (747-400) allowed for one stop Sydney-Singapore-London, and consumers adopted that as the norm.
So I fully expect consumers to adopt Sunrise as the norm for people travelling to major European cities. Perth residents have embraced QF9 as the norm to get to LHR, and vice versa. I expect SYD-SIN-LHR to remain, probably on a standard A350, but it could be repositioned purely into a revenue service tapping into the Asian market, similar EK's DXB-SIN-MEL service, as opposed to a fuel stop. And as other people have pointed out, PER is also likely to remain as it's similar to Australians visiting California (business, tourist and transit destination) before travelling to the eastern USA, fundamentally different to a transit-oriented stopover in a different country. So it's all in Qantas' favour I think.