Seven ships, even though a major expansion to their supply, still doesn't give them enough ships to cover everywhere people would like to see them, but my thoughts include:
I hope they add more specialty restaurants, including some open to families. One of the things my family loves about RCCL is that our whole family can go to the specialty options. (I'm all for keeping Palo and Remy for only adults, but an all ages option would be a nice addition).
I think it is highly unlikely that they will send a ship full time to Asia without a casino and smoking allowed on board, and I would be very surprised (beyond surprised, actually) if
DCL ever added those things.
I hope they keep at least two ships in the Caribbean full time so they can add new ports and itineraries. It would also be interesting to see if they'd ever locate one out of Galveston full time. While I know their Wonder sailings have not done particularly well, I think that's because they'd come for a while and then leave. RCCL's Liberty seems to do well and is generally booked up, so there seems to be a market if there is a consistent supply.
I don't think this is likely, but given DCL's "classic ocean liner" aesthetic, it would be interesting to see if they'd ever have a ship that makes transatlantic sailings on a regular basis, a la Cunard's Queen Mary II. They could even do it as a triangle, where the first cruise goes NYC to Southampton, then the ship goes from Southampton to Florida (Port Canaveral or Miami), then the ship goes from Florida to NYC (via Bermuda--although would that qualify as a "distant port"?) and then from NYC either back to Southampton OR back to Florida (again, via Bermuda, if that's legal) and then from Florida to Southampton. If Bermuda doesn't count as a distant port, then they could just go NYC--Southampton, Southampton--Florida, Florida--Southampton, Southampton--NYC.
Basically, my thinking with that is that while they may not be able to fill the ship to go transatlantic between the same ports every week, if they alternated ports it might fill the rooms. There are a lot of people, particularly older people, who enjoy the transatlantic cruises and if they were an actual itinerary (rather than just repositioning cruises) they might do well. But there's also a reason I'm not in the travel planning business so I'm more likely to be wrong than I am to be right. I'd love to do one during the summer with our family.