I would submit that hell is eternal.
Jesus was simply using picture language in Isa 66:24. How can spiritual beings like the devil or the false prophet be burned to nothing. How can you annihilate "a spirit". I would submit that hell is simpy separation from God and not annihilation..(2 Thess 1:9 They will be punished with eternal destruction (olethros), forever separated from the Lord and from his glorious power.) And as we all know, the word "olethros" does not mean annihilation.
Destruction (3639)(olethros from ollumi = to destroy. Derivative = apollumi = destroy utterly or fully and has to do with that which is ruined and is no longer usable for its intended purpose) is a state of utter and hopeless ruin and the end of all that gives worth to human existence! Do not confuse with a state of annihilation (and non-existence so that there is no longer an actual personal perception) for olethros signifies an unavoidable, very real experience of distress and torment! The destruction Paul warns about is a time of unavoidable distress, disaster and ruin. This destruction will not be a loss of being but rather a loss of well-being. The idea of olethros is to suffer the loss of all that gives worth to existence.
Isa 66:24 Picture, figurative, image language...
Their worm shall not die, neither shall their fire be quenched (comp. Mark 9:44, 46, 48). It cannot be by chance that the evangelical prophet concludes his glorious prophecy with this terrible note of warning. Either he was divinely directed thus to terminate his teaching, or he felt the need that there was of his emphasizing all the many warnings dispersed throughout his "book" by a final, never-to-be-forgotten picture. The undying worm and the quenchless fire - images introduced by him - became appropriated thenceforth to the final condition of impenitent sinners (Jud. 16:17; Ecclus. 7:17), and were even adopted by our Lord himself in the same connection (Mark 9.). The incongruity of the two images shows that they are not to be understood literally; but both alike imply everlasting continuance, and are incompatible with either of the two modern heresies of universalism or annihilationism.
What he emphasises is the eternal antagonism between the righteousness of God and man’s unrighteousness, and this involves the punishment of the latter as long as it exists. In any case there is a strange solemnity in this being the last word of the prophet’s book of revelation, even as there is a like awfulness in the picture of the final judgment, which appears in Matthew 25:46, at all but the close of our Lord’s public teaching. Cheyne quotes a singular rubric of the Jewish ritual, that when this chapter, or Ecclesiastes 12, or Malachi 3, was read in the synagogue, the last verse but one should be repeated after the last, so that mercy might appear as in the end triumphant after and over judgment.
Verse 24
This verse describes a terrible scene. It refers to the deep narrow valley called Hinnom. This valley is near to *Jerusalem, on the south side. (The *New Testament uses the *Greek word Gehenna for the *Hebrew word Hinnom – see Matthew 10:28). In the Hinnom Valley, two wicked kings of Israel burned their sons as a *sacrifice to false gods (Ahaz, see 2 Chronicles 28:3; Manasseh, see 2 Chronicles 33:6). And other people copied this wicked behaviour (see Jeremiah 7:32; 19:5-6; 32:35).
Later, the inhabitants of *Jerusalem threw their rubbish into the Hinnom Valley. What worms did not eat, fire destroyed. The fire never went out. Soon, what happened became powerful picture language to describe Hell. Jesus uses this verse, to mean ‘to *destroy totally’ (see Mark 9:48). Isaiah 66:24 is describing those people who refuse to serve God. They refuse to obey God’s instructions. But God is the origin of life. So these people have removed themselves from the God who gave them life. The verse describes their punishment as the extreme opposite of life. They have brought about their own terrible punishment. And that punishment is death that lasts for all time. (See Luke 16:19-31; 2 Thessalonians 1:9-10.)
Isaiah 66:24. And they shall go forth — Namely, those who had joined themselves to the communion of the church spoken of in the preceding verses; and look upon the carcasses of the men that have sinned against me — Meaning chiefly the unbelieving Jews who rejected Christ and his gospel, including, however, all impenitent sinners, and especially all the enemies and persecutors of God’s truth and people. By looking upon their carcasses is meant beholding the dreadful vengeance taken on them. This is here represented in figurative language. The misery is described by an allusion to the frightful spectacle of a field of battle covered with the carcasses of the slain, which lie rotting upon the ground, full of worms, crawling about them, and feeding on them. It seems the Lord, by his prophet, first intends to set forth the dreadful temporal calamities that should come upon the Jews, in the destruction of their city and nation by the Romans; in which destruction, as has been intimated in the note on Isaiah 66:16, not less than between two and three millions, first and last, were cut off by the sword, famine, and pestilence. But when it is added, for their worm shall not die, neither shall their fire be quenched, it is certain the punishment of the wicked in the world to come is chiefly intended. These words, it is well known, are applied by our Saviour, (Mark 9:44,) to express the everlasting punishment of the wicked in Gehenna, or hell, so called, in allusion to the valley of Hinnom, the place where the idolatrous Jews celebrated that horrible rite of making their children pass through the fire, that is, of burning them in sacrifice to Moloch; concerning which place see note Isaiah 30:33. “Our Saviour,” says Bishop Lowth, expressed the state of the blessed by sensible images; such as paradise, Abraham’s bosom, or, which is the same thing, a place to recline next to Abraham at table, in the kingdom of heaven; (see Matthew 8:11; John 13:23
for we could not possibly have any conception of it, but by analogy from worldly objects: in like manner he expressed the place of torment under the image of Gehenna; and the punishment of the wicked by the worm, which there preyed on the carcasses, and the fire, which consumed the wretched victims. Marking, however, in the strongest manner, the difference between Gehenna and the invisible place of torment: namely, that in the former, the suffering is transient; the worm itself, that preys on the body, dies: whereas, in the figurative Gehenna, the instruments of punishment shall be everlasting, and the suffering without end; for there the worm dieth not, and the fire is not quenched. “These emblematical images, expressing heaven and hell, were in use among the Jews before our Saviour’s time; and in using them, he complied with their notions. Blessed is he that shall eat bread in the kingdom of God, says the Jew to our Saviour, Luke 14:15. And, in regard to Gehenna, the Chaldee paraphrast renders everlasting, or continual burnings, by the Gehenna of everlasting fire. And before this time the son of Sirach (Sir 7:17) had said, The vengeance of the ungodly is fire and worms. So likewise the author of the book of Judith, ‘Wo to the nation rising up against my kindred, the Lord Almighty will take vengeance on them in the day of judgment, putting fire and worms in their flesh:’ Jdt 16:17, manifestly referring to the same emblem.”