What % of people, who go on cruises are 65 and over?
ALL of us!!
That would vary from Cruise ship, time of year, destinations and days length of the cruise.
IMHO the longer the cruise, the older the passengers.
The more expensive the cruise, the older the passengers.
Assuming a 7 day or longer cruise, the smaller size of the cruise ship, the older the passengers.
So vaccination requirements will affect cruise lines differently. Actually helping out some ships, and reducing passengers on others.
More problems for itinerary and length of cruises to be worked out, after the Lines figure out where there target audience is.
IMHO the Cruise Lines are not going to have the massive cruise base they had in 2019. -Tom