Let me make an observation. Many mission organizations do not value leadership on their teams or fields. It is a holdover from the past where missionaries viewed themselves as independent contractors rather than a part of an organization or team. In that culture, when there needs to be leadership, one elects someone who will basically leave you alone and the criterion is often that they have been on the field a long time (paid their dues) or it is their turn (among those who have paid their dues) with little evaluation as to whether they are truly leaders or not.
Let me make a second observation. Not valuing leadership in missions means that those missions are not truly concerned about good strategy, seeing significant fruit or missional effectiveness. The long term result will be the decline and eventual death of those missions because while they don't value strategy and missional effectiveness, the individuals and churches who pay the bills do - a lot. And they will not continue to pay for ineffective missionaries or strategies.
Furthermore, long experience on the field does not equal leadership skill. All it equals is long experience on the field. Veteran missionaries often resist leadership from individuals who don't have that long experience but they miss the point. Good leaders release others into focused, missional, strategic leadership. They don't need to know what a veteran missionary knows because they use the expertise of the team an determine where they go and then they align all team members in a direction that is likely to be fruitful.
Leadership should be seen as a skill in itself. Good leaders don't know everything, in fact they may not know a lot. But they do know how to position people for success, build a team that is pulling in the same direction, solve problems and ensure there is a healthy strategy. That is true in business and industry, just as it is in missions. The job of leaders is not to know everything. It is to take the corporate wisdom of those involved and help craft direction and strategy and alignment.
In industry when business is in trouble, the board often will bring in a leader who has no prior experience in that field. What they do have is leadership skill and the ability to access, get the right people in the right seat on the right bus, determine what needs to be done in concert with the corporate wisdom of good people and turn the business around.
Missions that will thrive and survive in the years to come will do so because they have courageous leaders who help lead missional teams toward fruitful ministry. Ignore leadership and your mission is destined to fail. Value it and you will move forward.
One final observation. All Christian movements globally require good leadership. That is why Paul spent so much time developing leaders. Missions who don't understand good leadership will never be able to develop indigineous leaders. And if you don't do that, you will not leave behind fruit that will last.