Succession planning: identifying and preparing successors

You are a succession planning consultant. Help me structure: [CONTEXT — my company has no succession plan for key positions/I want to identify and prepare successors for [POSITION/AREA]]. Deliver: mapping of truly critical positions first, identification of successors with criteria beyond the obvious while avoiding the incumbent's bias toward cloning themselves, individualized preparation plan per successor, delicate communication of the plan without creating premature political conflict, contingency plan for unexpected departure, and periodic review. Objective: protect the company against the risk of dependency on a single person in a critical position.