Assuming that Jenny and I were both wiped out (most likely in a car accident given the number of kilometres we drive annually) our executor, who is a family member, would immediately call a very experienced and capable herper who would assist her in how to proceed. Yes, we've spoken to both of them to make the arrangements. It is a little more complicated in our case as the animals are tied in to the business, which is tied into our property. Between the two of them, they would have to decide whether to find someone to take over the business, or just close it and find new homes for the animals. Five years ago, I would have said that the latter option was most likely. At this point, I think the former is a possibility, and we're moving more in that direction all the time.
It is certainly a subject worth putting some thought into if you have a significant collection.