I would offer. Their eternal destiny is either in death or life. Death is the opposite of life .Not a extension (limbo, purgatory).
God did not say you will surely suffer forever. Clearly he said surely die.
I think when a person makes smoke into a spiritual living substance as that which rises forever.This is where the difference is. It becomes a matter of faith. . the unseen revealed.. . . or not of us
The smoke of death rises up never to become spirit life for ever and ever more.
It would be like when Aaron's two Sons having a desire to enter the kingdom of priests. They added their own self edifying idea of adding strange fire as a personal touch a oral tradition of men. They were consumed and their ceremonial clothes did not have a hint of smoke. It was like God had smelt death .The aroma of self righteousness did not appeal to His good pleasure.
I would think only if we have the aroma of His Son the first born. like Jacob when he was given Esau fragrance blessing. A wonderful parable .
And he came near, and kissed him: and he smelled the smell of his raiment, and blessed him, and said, See, the smell of my son is as the smell of a field which the Lord hath blessed: Therefore God give thee of the dew of heaven, and the fatness of the earth, and plenty of corn and wine: Let people serve thee, and nations bow down to thee: be lord over thy brethren, and let thy mother's sons bow down to thee: cursed be every one that curseth thee, and blessed be he that blesseth thee. Genisis 27:27-29
The dew of heaven, and the fatness of the earth, and plenty of corn and wine: The gospel that blesses the bride of Christ.
Like in Daniel when four were walking around no smell of death. . .
I would add one more idea to support what I would call . . . . the doctrine of the sweet savior of Christ.
2 Corinthians 2:15-17 King James Version (KJV) For we are unto God a sweet savour of Christ, in them that are saved, and in them that perish: To the one we are the savour of death unto death; and to the other the savour of life unto life. And who is sufficient for these things? For we are not as many, which corrupt the word of God: but as of sincerity, but as of God, in the sight of God speak we in Christ.