I'm convinced a key aspect of Christian leadership is that it reproduces itself. Leadership is not innate but a gift given by God. If God calls and enables you to lead, He will also call and enable others. You are not irreplaceable.
I see this idea present in creation: God makes humanity in his image, we are made to be like him.
The Bible is full of stories of unlikely people called and sent by God.
Another place is one of the hardest to believe or understand promises Jesus ever made. "Very truly I tell you, whoever believes in me will do the works I have been doing, and they will do even greater things than these, because I am going to the Father." John 14:12. If anyone could think of himself as irreplaceable, it would be Jesus, the Son of God. But he believes and promises that the same works he does, each of us can do because he has gone to the Father.
The principle appears again in Paul's counsel to Timothy. "And the things you have heard me say in the presence of many witnesses entrust to reliable people who will also be qualified to teach others." (2 Timothy 2:2). Christian leaders should be watching out for people who can be gifted to become leaders, and encouraging and training them, encouraging them to lead.
This reminds me of my recently discovered missionary hero, George Leslie Mackay, who did focus on replacing himself as the leader of the Taiwanese churches he planted.