The WTS does try to weasel out of whether people who die at Armageddon, could be resurrected:
"When the oncoming battle of Armageddon strikes in its fury and with its desolations, many devoted Christians will be in their old age or in an infirm condition. Hence it may be that during the progress of that battle with all the conditions which it will produce on and around the earth, many Christian aged, weak in constitution, or with poor hearts, may die from sheer natural causes. When we read the prophetic accounts of that battle, for instance, Psalm 46, telling how the earth will be moved, the mountains be carried into the midst of the sea, the waters roaring and showing great agitation so that even the mountains shake with the swelling thereof, we can see it will be a time that will be hard on the hearts and physical constitutions of even the hardiest of persons. We may have to undergo many privations in common with the people of the world, including food reductions, exposure to the heartless elements, etc., so that it will be a strenuous time, taxing our physical powers. Some, because of physical condition, age, or other circumstances, may prove no more able to endure the hardships of Armageddon than others." W1951 5/15 p. 299 (still thinking today.
The WTS reasons that only those directly executed by Jesus, the angels, and the anointed in heaven definitely will die forever, but as humans on earth, Jehovah's witnesses will not know who are not in the group, until after Armageddon and the resurrected ones come back. Interesting way to say something that is not in their Bible.