Watchtower 8/1, 1959:
Jesus here applied the expression "mild-tempered" or "meek" to his disciples of that time who were in line for the heavenly kingdom. He was the chief meek one among them and their example. Hebrews 1:1, 2 and 2:5, 6 show that Jesus inherits the earth or takes over the possession of it. His disciples were made his joint heirs in the Kingdom and enter into this inheritance or possession of the earth with him. Hence Matthew 5:5 does not strictly apply to the "other sheep." However, it has been quoted in connection with them and properly so because they must be meek or mild-tempered ones in imitation of Jesus Christ, and it is only because of being such that they will be allowed to live on the earth in the new world. They do not take over possession of the earth any more than Adam did in the garden of Eden, but Matthew 5:5 can nevertheless be given a general application in that they hold the earth in trust for the chief Heir, the Lord Jesus Christ. To this extent they enter into an inheritance. They enjoy the realm of the King. As Jesus said in the parable of the sheep and goats: "Come, you who have my Father’s blessing, inherit the kingdom prepared for you from the world’s foundation." (Matt. 25:34) So it is not wrong to use this scripture in a general sense in speaking of the blessings that await the "other sheep" in the new world.
10/15, 1991:
Jesus pronounced the mild-tempered happy because they will inherit the earth. As the perfectly mild-tempered Son of God, Jesus is the Chief Inheritor of the earth. (Psalm 2:8; Matthew 11:29; Hebrews 1:1, 2; 2:5-9) But as the Messianic "son of man," he was to have associate rulers in his heavenly Kingdom. (Daniel 7:13, 14, 22, 27) As Christ’s "joint heirs," these anointed mild-tempered ones will share in his inheritance of the earth. (Romans 8:17) Other mild-tempered, sheeplike people will enjoy eternal life in Paradise in the Kingdom’s earthly realm. (Matthew 25:33, 34, 46; Luke 23:43) That prospect makes them happy indeed.
Seems the writers are very lazy these days...