This was one teaching I never really could rationalise - luckily I hardly ever remember any householder mentioning it when I was on the ministry as I would have really struggled to justify it.
The teaching that all non-JWs will be annihilated at Armageddon together with not very active JWs who don't quite make the cut ( the so-called "Kevinly class") is still the Societies teaching , but there is no doubt that the rhetoric from the past is very much toned down.
No longer do we see pictures of babies being thrown into chasms in the earth or husbands and wives desperately hugging each other awaiting their imminent violent deaths as Jesus and the angels go around killing people. The "wicked" being destroyed , if depicted at all , tend to be obvious baddies with knives or guns and beards and jeans!
Note the official JW dot org response , which is rather disingenuous to say the least.
https://www.jw.org/en/jehovahs-witnesses/faq/who-saved/