I can see them doing this as a new tactic to make JWs think that Armageddon s imminent, which is something that they are always trying to o do.
The July 2015 watchtower provides the clue and introduced new light regarding the GT. They said that witnessing work in declaring the good news would come to a stop and JWs would then begin to give a judgement message. They had always taught that the good news of the kingdom would be preached right to the end and they also said that this message includes a judgement message, now they are separate and are being taught at different times.
They would introduce the new name saying that they are making the change in order to prepare for the GT which is about to happen so soon that they need to prepare now. During the GT they will no longer be witnesses as the preaching work will have stopped. Being worshippers of God at that time will be more important than anything.