The real question is whether there is enough corporate demand from Melbourne to London to sustain a daily service because if Sydney fails then Melbourne won't work. Most multinationals and major corporate HQs are in Sydney, and they are the ones paying cash for business class.
Many J class passengers are retirees or couples, sometimes the latter even with children.
The days of the J cabin being exclusively for corporate flyers such as fund managers have long passed.
Melbourne is home to two of the largest four Oz-domiciled banks in NAB and ANZ, many manufacturers who generate a lot of freight/logistics, sporting-related entities (the powerhouse that is the AFL - a more popular code than Rugby League), transport companies (think Linfox)...list goes on.
Plus special sporting events held in Melbourne (Australian Grand Prix, Australian Open, Boxing Day Test, Melbourne Cup) attract far more visitors than anything sporting in Sydney.
So not as if there's nil corporate demand from MEL.
Melbourne is constantly ignored by Qantas' international division: no flights to JFK, LHR, MNL, JNB, SCL and HND to name a few.
QFi must have gained market share since 28 February 2026 due to the problems affecting EK, QR and EY with the Iran v Israel/USA conflict but this (God willing) is a temporary setback.