I believe the Watchtower would say that all those in their graves i.e., memorial tombs, who die before the tribulation and Armageddon, will automatically be resurrected and given a chance at life during the 1000 years.
If that is the case, the question I would want answered is: What advantage is there of becoming a JW?
Witnesses probably would say that if you heard their 1914 - 1919 life-saving message and reject it, then you will not be in your memorial tomb and you will not be resurrected.
So they actually would be saving or giving a lot more people a chance at life in the new system if they just keep the "good Watchtower news" to themselves.