It is better to have a contingency plan to assist employees in case of a disaster. HR should help employees and enable employees to help each other. Leaders faced with any unplanned circumstances would hopefully have enough time to develop a strong plan of action to implement the changes. Their first step in the plan is to help the company transition smoothly. A great leader starts with a great team, they can do nothing without the help of those working for them and with them.
What about downsizing should the company be prepared for an unfortunate event such as RIF (Reduction-In-Force)