Every company board has talked about a succession plan - at least if they are responsible and intelligent. However, succession planning should not be limited to executives. Every front line manager should have a succession plan as well.
This doesn't have to be a formal process, but it should be one that is reviewed at least yearly (I would recommend at least quarterly).
What needs to be part of the succession plan?
A list of people who either have expressed interest in a promotion or who the manager believes has the potential to be promoted. Notice that this will require the manager to have discussions with employees on their future goals.
A list of the key behaviors, skills, and competencies that is needed for the manager role - not just now, but in the future.
A plan for how people are being developed to gain the key behaviors, skills, and competencies.
The important thing in my eyes is that the process doesn't become a coronation. You aren't promising the role to anyone. However, you are trying to make sure that the role can be filled properly with someone internal if that is what the company decides.
CEOs don't always get to pick their successor, but they can influence the process. The same applies to your role.