If you want to do an
ABD river cruise, the chance of cancellation is low since I assume the cruises will run no matter the number of guests. When I booked an ABD Rhine cruise, the Vacationista told me that trip was "guaranteed to go". I would be more concerned about water levels in the river you select.
If you want a land trip, you can ask a Vacationista how many guests have already booked. While ABD doesn't say what the minimum is, the guess is if the trip is at least half full then it is likely to go. For the Morocco trip I'm currently reporting on, there was another Morocco trip that was 3 days ahead of my group. That trip has 17 guests and it still occurred, with 2 guides.
Also, you can buy your airfare through the ABD air department. That way, if ABD cancels then they will refund your trip and airfare. Yes, it would be inconvenient in not leaving much time to plan a replacement but at least you would get all your money back.
We've had two reports on this board of trips where the activities significantly deviated from the posted itinerary, and both were during the Xmas-New Year's week. But not every trip has been affected like that. You can see my ABD New Zealand report which started on Xmas Dec. 2022, and the Morocco trip that I'm still writing the report for.