This is possibly preparing the troops for the shock of the first year when stats show an actual decline, rather than an increase, in the number of JWs worldwide - which will come. eventually.
However, I'm still baffled by the comment, and think it unlikely to be given as an official statement, since it would present JWs with an excuse not to go out in field service anymore.
Watchtower July 1, 2002, p.13, paragraph 17-19:
Now is the time for Jehovah to express mercy to his anointed servants and their other sheep companions.
The evidence that this is so is the extraordinary increase with which he has blessed them…
18. Each year, hundreds of thousands of additional "foreigners" associate with Jehovah's organisation, and the way will remain open for many more to follow them. Jehovah says to Zion: "Your gates will actually be kept open constantly; they will not be closed even by day or by night, in order to bring to you the resources of the nations, and their kings will be taking the lead" (Isaiah 60:11) Some opposers try to close those 'gates,' but we know that they cannot succeed.
Jehovah himself has said that one way or another, the gates will stay open. The increase will continue.