Actually if you read the
DCL press release, they listed all the changes that will happen during DRY DOCK, the only additional issue was that Carioca's is going to take longer to make over so they will shift the MDR service to Cabanas on a few of the cruises in order to get a head start on the refresh Carioca's. There was NOTHING said about closing the other venues during upcoming cruises to do any work, those areas will be worked on during the dry dock period in Feb/March when the ship is taken OUT of service.
In addition they won't just be shoving people into Cabanas and expecting them to go there to eat like it was regular nightly service, the space will be treated as a standard MDR and your wait staff and table arrangements will be as if you were in the assigned MDR in your rotation. DCL isn't going to make such changes with out trying to make the venue change less than what it would normally be, expecting on board credit or some kind of compensation (even after they've notified you ahead of your cruise) isn't reasonable. Read the cruise contract, by booking the cruise you agree that any changes during your cruise other than emergencies, weather related port changes or dangerous circumstances are acceptable and DCL is not compelled to refund or compensate for giving advance notice of changes, that will not affect the overall outcome of your cruise.