The trip scheduled for the week before ours (the one we tried to switch to but ABD wanted to charge me $1000 more) has disappeared from the website. I believe that trip had 30+ guests booked when I inquired about changing. It all makes sense, but I wouldn't expect ABD to take down a trip with only 20 guests booked as long as people could still conceivably book and get airline tickets. So, I'm not sure relying on the website would always be a reliable way to determine if a trip is guaranteed or not. I would think the odds of our trip being cancelled at this point are pretty low, but as long as ABD has this stupid cancellation policy, I won't feel confident until we are on the plane.
I can't think of any reasons why ABD couldn't guarantee our trip at the 30-day mark, other than they just don't want to, and that REALLY irritates me.