A few points to add:
1.
DCL is VERY conservative. Their ships have very high operating costs, and they must see other mainstream North American cruise lines do it successfully before taking the plunge themselves.
2. IF they ever went to Australia/NZ, it would be the Wonder doing so on one of the following two routes with several one-way cruises:
Alaska > Hawaii > Japan > HK > Singapore > Australia/NZ
Alaska > Hawaii > FP/South Pacific >Australia/NZ
3. They key seasons to do so in are from Sep to mid Dec, or from Jan to early Mar. They really want all their ships in North America over the December holidays and March to April school breaks.
4. The ABD itineraries aren't a good representation of what the cruise line will do - and in fact, sometimes they will use ABD to rope in the regions where they don't want to take a ship.
5. Asian language barriers are irrelevant for Disney. The Shanghai and Tokyo DL have become two of their highest margin properties worldwide.
6. NCL's Asian troubles are often misquoted. They took the ship to Alaska because of the analyst pressure to deploy more capacity there in the summer. Growing pains, I suppose, before they really understood the Asian market! Recently, they have dropped $100 million on the Spirit to refurbish it exclusively for Japan and Asia.