In the past if there were enough people requesting a shore excursion that is full they arrange another bus etc and you can go...If youre on a waiting list you usually end up going...of course it depends on what is involved etc...
However arranging spots for every passenger on board may be difficult...
Since about half the ship usually go off on their own or take independent tours, the meeting places on board and on the pier are going to be zoos...
Personally I take 1 SE a cruise and sometimes none...unless I’m in Europe/TA...
In Alaska last year I took a Carnival SE at every port but that was unusual and I had heaps of OBC for that cruise...
I know how badly you want to get a cruise in, an have had so many cancelled, but If you are going between now and the Spring of 2021 on Seabourn or Azamara they have just cancelled all their trips now till the Spring of 2021.
MSC, the 4th largest Cruise line has just cancelled all USA cruises to the Caribbean and Bahamas. -Tom