That will be up to the CDC on cruises touching the US and the various countries visited. My guess it will be a long time before regulations are loosened. Host countries will probably be quicker to loosen regulations than the CDC
FWIW, Canada has already stated that cruising in their territorial waters won’t be permitted until next year, at the earliest.
We tend to think of the Caribbean and Mexico when discussing the cruise industry. But, Canada, Alaska and the Pacific Northwest had a robust cruise industry until the Chinese Communists destroyed it.
Why will it be up to CDC?
Who granted them that authority?