There are two phases in your career development in the corporate life:
1) Make yourself in-dispensable.
In the early development stage, you start to build your area of competence, try to do as much as possible and learn every thing you can and then finally got into the stage that you can virtually not be replaced easily. What can you do with it? Every thing. You can ask for a motivation (read: salary increase), for a development plan (read: paid training courses, on the job degree, e.g. MBA), for a flexible working time (read: more day-offs). Or even career development (read: promotion): Since you can not be replaced (please make sure that this is true also in the mind of your boss), he or she would be willing to accept your requirements.
2) Make yourself dispensable
When you got promoted and have team(s) working for you, your job is to make sure that the work will be done well with less your involvement as possible. When you take three weeks vacation, you can switch off the cell phone with the absolute consciousness that when you return every thing will be fine. What should you do with your time?
a) Clarify with your manager what exactly the team should accomplish and how to measure those accomplishments.
b) Structure the work such that every one can do their work in their area of excellence.
c) Make sure that the needs of those people are made, so they feel happy to come to the office.
If your job is doing well, you will have in fact less and less to do. So what should you do next? Three things:
d) Market your organization.
f) Develop your organization to next level of challenge.
e) Prepare for the next level of the job for yourself.
By practicing “Making yourself dispensable” you indeed take a risk that your manager may think that you are irrelevant for the organization. This risk is however worth taking, because he might not be the right leader who will take you anywhere. And you should leave him and find a better place to grow anyhow.