The 4 2021 canceled cruises, Spirit, Valor, Magic and Paradise, are all due to the drydock availibilty per Christine Duffy. They were scheduled but with Covid, the dock space isnt available, so everyone is reshuffling their dates. Id expect
RCCL,NCL and others are all going to have the same issues. Even Disney. Has nothing to do with Covid updates. Come to think of it, there probably isnt any covid updates for the ships. Possibly in the future but nothing is being done at the moment. RCCL and I think it was NCL was working on a plan to get ahead of the curve, and light a fire under CDC, but I dont think anything has come up solid yet.
Using Freeport as an example, a lot of lines including Disney will fly in specialists from all over the world to do work on specific things. Like Italian stone masons for the marble, technicians for the main electrical and the main engines from the manufacturer etc. If they cant get foreign contractors to the docks, or workers in general, they cant get the work done. Add in class requirements, that are fairly strict, and things go from bad to worse. Its possible they can get extensions, but its a lot of ships to get squared away, and were not talking just cruise ships. Tankers, cargo ships, RORO ships, transports all need dock space at the same time.