In a stark wilderness, an old man passes on all of his accumulated wisdom, experience, and courage to a younger man. The old man's journey is over; he goes to his death having known what exactly it means to live with fullness and faith. The young man looks forward to the future, and looks to the vast multitude behind him, and trusts that what the old man has said is indeed true.
So Moses passes on the mantle of leadership to Joshua. A young man for an old man. Although Moses did not complete the entire journey of the Israelites, he had run the course of his journey. He dies without setting foot on the Promised Land. This broad and good swath of land will always remain just that for Moses, a Promise.
We too have a land of promise. The Jordan River of death stands between the Now and the Later. The priests, bishops, holy men and holy women that we follow on the way there may not always be the ones leading us. They may die before our arrival. And that's okay, because we have faith that the Lord will raise up among us new leaders to see us through. Then, eventually, we will have no need of these earnest, good-hearted men and women; we will have the Great Shepherd himself herding us across that Jordan River that lies between life, and life after life.