The Disney Wonder was on the provisional Port Melbourne cruise schedule, but has since been removed, further suggesting
DCL is pulling out of the Australian market at the end of this current season. It still shows up on the Sydney port schedule but there is a large gap from Nov 5 - Dember 29 which is where Melbourne should have been so it's likely Melbourne just updated faster than Sydney.
Such a shame we had a great time on our sailings in Sydney but they were worryingly quiet so makes sense to move out of the market.