I read you bentley - but I think it would be a much better solution for people to take responsibility and always make advanced arrangements for the pet, just in case, just as one does with children. This is what we did with our children, had a reciprocal arrangement with sil and bil. We've agreed to take on grand-children if ever - with finance in place for help, in the shape of a nanny/housekeeper. And our dog and cat have a good home in place just in case, with finance to support them to the end.
But I do agree that it is the pet 'owner' to ensure everything is in place for 'when and if', with people one trusts. Far too many pets end up in refuges/RSPCA because people do not think ahead and take responsibility. A pet is of great solace for a person on their own.