Qantas has had many years to cement Melbourne as an alternative hub but has failed to do so.
It remains 'Air Sydney' even though (depending on where statistical boundaries are drawn) Melbourne is on track to exceed Sydney's population in a few short years.
Sydney with its strengths in finance and investments is Australia's only 'international city' but it's hard to believe there isn't a substantial reservoir of wealth in Melbourne that would support numerous premium class seats each day and ensure yields were sufficiently attractive. One only has to look at the success of SQ ex MEL (excellent occupied seat percentages, five daily flights each way) and (while probably still affected by the Iran-USA/Israel war) EK and QR, plus a plethora of other Asian carriers such as CX to see how treating Melbourne with the respect it deserves pays dividends for airlines.