There is so much supposition that goes along with this but you would have to figure that the cruise line would treat Covid as any other health problem. Like the flu. If you are vaccinated and boosted then you may not even have symptoms. Likewise other passengers may catch it but they may not know it etc, do you obsess about flu, colds etc when on a cruise? You probably take reasonable precautions. Few people who are fully vaccinated (and boosted) become hospitalized, ventilated except high risk individuals who must assess their own risk tolerance - like for any health problems.
It would also depend on the rules of the countries on the itinerary.
There are many who are ready to get on with their lives after over two years.
Several of the vlogs and blogs have suggested that fear and the consequences of testing positive on the pre cruise Covid test is one leading barriers to people resuming cruising - not the fear of getting or managing Covid itself. Therapeutics are available now, too.