Make way for the next generation

The Lord appointed a tribe as his special servants (Num 8:14). The Levites did not inherit any land. The Lord was their portion. They served in the tabernacle or temple and were supported by the rest of the people through tithes and offerings. They were required to retire from official duties at age 50, but they could continue to serve in support roles (Num 8:23-26). Why would the Lord move them out of the lead when they were at their prime? Quality ministry requires a great deal of energy (2Co 12:15). No matter how dedicated the minister, he is subject to burn out. Also, I suspect the Lord wanted them to make room for the next generation of ministers and focus on training them (2Ti 2:2, 4:6).