Actually chieftain concept taking over after the GB leave was discussed in a 1999 WT study article based on a talk at the DC in 1998
*** w99 2/1 p. 19 Our Treasure in Earthen Vessels ***
As the number of the spirit-anointed remnant on earth has decreased, mature brothers of the great crowd have been given spiritual oversight of almost all the congregations worldwide. And as the last aged anointed Witnesses finish their earthly course, princely sa·rim´ of the other sheep will have been well trained to carry out administrative duties as the chieftain class on earth.—Ezekiel 44:3; Isaiah 32:1.
*** w99 1/15 p. 9 Determined to Follow God’s Way of Life ***
This was the theme of the convention’s third day. (Isaiah 30:21) The program began with an exciting symposium of three talks, focusing on Ezekiel’s temple vision. This vision has great meaning for God’s people today, since it relates to pure worship in our time. A key to understanding the vision is this: Jehovah’s great spiritual temple represents his arrangement for pure worship. As the features of the vision were discussed, listeners pondered their activity in support of the work done by loving overseers of the anointed remnant and by the prospective members of the chieftain class.
*** w99 3/1 p. 17 "The Temple" and "the Chieftain" Today ***
Now an intriguing question arises. Whom, then, does the chieftain represent? Since he is spoken of both as an individual and as a group, we may assume that he represents a class of men. (Ezekiel 44:3; 45:8, 9) But who? Surely not the anointed. In the vision, he works closely with the priesthood, but he is not one of them. Unlike the priestly class, he is given an inheritance in the land and thus has a future here on earth, not in heaven. (Ezekiel 48:21) Further, Ezekiel 46:10 says: "As regards the chieftain in their midst, when they [the nonpriestly tribes] come in [to the temple’s outer courtyard], he should come in; and when they go out, he should go out." He does not enter the inner courtyard but worships in the outer courtyard, entering and exiting the temple with the people. These factors decidedly place the chieftain among the great crowd of the other sheep.
Clearly, the chieftain was to submit to the spiritual services and leadership of the priests. It is fitting, then, that in modern times the anointed have taken the lead in pure worship. For example, the members of the Governing Body of Jehovah’s Witnesses have been chosen from among them. Such faithful anointed elders have been training the developing chieftain class for decades, preparing prospective members of this class for the day when they will be delegated their full measure of authority in God’s new world to come.
In Bible times some chieftains had much authority, others less. Today, elders of the great crowd have widely varying responsibilities. Some serve in one congregation; others serve many congregations as traveling overseers; others serve whole countries as Branch Committee members; others directly assist various committees of the Governing Body. In the new world, Jesus will appoint "princes in all the earth" to take the lead among Jehovah’s worshipers on earth. (Psalm 45:16) No doubt he will select many of these from among the faithful elders of today. Because these men are proving themselves now, he will choose to entrust many with even greater privileges in the future when he reveals the role of the chieftain class in the new world.
*** w99 3/1 pp. 22-23 Jehovah’s Blessing on Our "Land" ***
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Also at that time, the apportioning of the land in Ezekiel’s vision will find its final fulfillment. Ezekiel saw the land properly allotted; likewise, each faithful Christian can be sure that he will have a place, an inheritance, in Paradise. Likely, the desire to have one’s own house to live in and care for will be fulfilled in an orderly way. (Isaiah 65:21; 1 Corinthians 14:33) The city that Ezekiel saw fittingly pictures the administrative arrangement that Jehovah purposes for the new earth. The anointed priestly class will no longer be physically present among mankind. The vision suggests as much by portraying the city in "profane" land at some distance from the temple. (Ezekiel 48:15)
While the 144,000 rule with Christ in heaven, the King is not without representatives on earth. His human subjects will benefit greatly from the loving guidance and direction of the chieftain class. However, the real seat of government will be, not on earth, but in heaven. Everyone on earth, including the chieftain class, will be in subjection to the Messianic Kingdom.—Daniel 2:44; 7:14, 18, 22.