This has been in the JW mythos for a long, long time. And that is, during the great tribulation, the “door would close”. Then JWs would cease preaching the good news and preach a message of judgement, basically telling people they were going to die.
There’s a verse in Revelation that talks about hailstones raining down, each one weighing a talent. Watchtower interprets this as the hard hitting message they would preach to people during the tribulation.
Of course, the 2018 change has nothing to do with it. But JWs are always looking at tealeaves in the pages of the Watchtower.