Well, a lot of ideas here are truly wishes upon a star.

Very fun to read! I would love a world cruise from Disney, but that's not gonna happen - even our wallet somehow can stomach one, lol. Their ships have such high operating costs that they have to be absolutely certain that an itinerary would sell before mounting one. If another cruise line hasn't sailed one, Disney won't even look at it.
What I would really like Disney to do is to spare a ship to spend the fall/winter in a different part of the world every year - particularly when all 7 ships are sailing.
For example, after Wonder is done Alaska and the Mexican itineraries in the fall, send it to Hawaii. It can then:
- Make a trans-pacific journey from Hawaii to Australia/NZ
- Spend the holiday season down under
- Relocate to Singapore in February and do the one-way itinerary between Singapore and HK
- Do the HK-Shanghai-Tokyo itineraries in March
- Circumnavigate Japan in its cherry blossom season in March/April
- Relocate to Hawaii at the end of April
- Return to Alaska in May
Then, the following winter, take one ship down to South America, circumnavigating the continent in the process. Do the Cape Horn itineraries a few times - and even a Panama Canal transit from Florida to Peru.
In yet another year, leave Magic or one ship in Europe and spend the fall or winter in the Mediterranean, including hitting Egypt, Israel, Turkey, etc. I would love for them to do a Suez Canal itinerary, but that takes two to three weeks one way - at the end of which is a region where Disney doesn't have any presence.