Puerto Plata has a lot of unpaved roads. In January, I nearly threw my back out because of the rough trip to our beach. If I ever return there, I would just hang out at the pool that's right at the pier.
The issue would be that this "World" cruise would have to use a Spirit-class ship. Alaska/Hawaii gets one, Tampa gets one, Mobile gets one for 6 months, and Baltimore another. Stretches this class a little thin.
Seems like either Grand Turk or Puerto Plata are the usual substitutes unless it's a short itinerary. I'm sure Royal would prefer two ships at CocoCay everyday, but Grand Turk is a better destination as you can spread out more. I guess RCCL is paying Carnival to use the port?
Costa has 9 ships left in their fleet with no new builds planned. Their oldest ship, the Fortuna, is now 21 years old. Maybe they get the old Mediterranea from Adora cruises in a few years if that cruise line doesn't start to get off the ground?
Paradise and Elation will be 30 years old in 2028. I wonder if any of the Costa ships might bounce over to Carnival by then. Costa seems to be slowly disappearing.