Players are scouted and developed, evaluated, signed, traded, and released/non-tendered. Coaches and managers are scouted and developed, evaluated, signed, hired away (although rarely for a lateral move) and fired/not renewed. The same thing that applies to players, coaches, and managers applies to all positions within the organization, right up to the general manager. Derek Falvey seems like a pretty intelligent fellow, so I expect that he knows all this and has contingency plans to follow in the event a member of the organization needs to be replaced for any reason.