On my recent performance review I was identified as a high performer with a low potential on a McKinsey 9 box matrix even though my leadership, motivation and entrepreneurial skills were all rated about 9/10 and overall sum was 90/100. The reason given to me for my low potential score (no chance of promotion) was that I would be too missed in the development team.
I have eight years of experience and a set of very specific skills needed for this industry. In my recent years I've done a lot to improve general processes in the company with very measurable results. My daily tasks include mentoring my younger colleagues and maintaining and setting standards for writing code and testing. I've felt ready for a next step in my career for a few years now.
What would be the best way to convince my company to promote me to a team leading or a similar position?