They're reiterating their recent change of view, i.e. finally deciding on the question, 'will some anointed survive into the new world or won't they?'. They've vascillated on this for decades.*
But the possibility of them surviving on earth beyond Armageddon raised scriptural conundrums - particularly in Revelation.
(Revelation 2:26, 27) . . .And to him that conquers and observes my deeds down to the end I will give authority over the nations, and he shall shepherd the people with an iron rod so that they will be broken to pieces like clay vessels, the same as I have received from my Father"
(Revelation 17:12-14) . . .“And the ten horns that you saw mean ten kings, who have not yet received a kingdom, but they do receive authority as kings one hour with the wild beast. These have one thought, and so they give their power and authority to the wild beast. These will battle with the Lamb, but, because he is Lord of lords and King of kings, the Lamb will conquer them. Also, those called and chosen and faithful with him [will do so].”
Revelation 19 describes the marriage of the Lamb, followed by the evening meal of the Lamb's marriage where the slaughtered comprise the main course (yum). Marriage first, then slaughtering, then eating. (Helluva wedding!)
So if some anointed are not gathered before Armageddon, how can a complete Bride be presented to the Lamb? How can Jesus fulfil his promise that the faithful anointed will smash the nations to pieces and conquer the 'ten horns' with him?
Therefore the GB has tidied up these loose ends. It has meant that they have had to adopt some kind of 'rapture' doctrine where the anointed remnant still on earth are transferred to heaven before Armageddon (1 Thess. 4:15-17). On this issue, the GB is more in keeping with scriptural teaching.
* w74 12/15 pp. 765-766 par. 36 Benefits and Rewards from Being Spiritually Secure
Only from the end of the year 1928 was the prospect opened up to the spiritual understanding of the anointed remnant of the “Israel of God” to survive the “war of the great day of God the Almighty” at Har–Magedon and enter here on earth into Jehovah’s righteous new order. (See The Watch Tower under date of December 15, 1928, page 376, paragraphs 35, 36.) And now, as the year 1975 opens up, some thousands of the anointed remnant, still alive on this earth, look ahead to realizing that joyful prospect. The increasing “great crowd” of their sheeplike companions look forward with them to entering the New Order without interruption of life. In the New Order Jehovah God will add to the “length of days” of the anointed remnant on earth to the point of satisfying the members thereof. It remains to be seen whether they will be yet retained here on earth to see the start of the resurrection of the earthly dead and to meet faithful witnesses of ancient, pre-Christian times. They would enjoy that, before being taken off the earthly scene to the heavenly reward with Christ.
w90 12/15 p. 30 Do You Remember?
□ Will some anointed Christians survive the “great tribulation” and live on earth for a time before being taken to heaven?—Revelation 7:14.
The Bible is not explicit on this. Some Bible accounts seem to suggest that anointed ones might live on into the new world. However, millions of those hoping to live forever on earth have received the training needed to get the new world under way. Hence, the small remnant would not be needed for this work, and God may choose to take them to heaven for “the marriage of the Lamb” after the executing of the religious harlot, “Babylon the Great.” (Revelation 18:2, 10; 19:2, 7, 8)—8/15, page 31.