The early Church fathers all believed that the book of the Apocalypse clearly spelt out the destruction of the harlot-city of Jerusalem (as we see referencing Hosea and Isaiah) and the new temple that is Christ
Absolutely incorrect. Irenaeus clearly did not hold this view. He spells this out in Book V, chapter 30 of Against Heresies. Of the Anti-Christ, he says "But he indicates the number of the name now, that when this man comes we may avoid him, being aware who he is." He speaks of the Anti-Christ as a future man and thus the Apocalypse in the context (as is Book V, 30) as all future events. Hippolytus does the same.
Irenaeus goes on to say: ""But when this Antichrist shall have devastated all things in this world, he will reign for three years and six months, and sit in the temple at Jerusalem; and then the Lord will come from heaven in the clouds, in the glory of the Father, sending this man and those who follow him into the lake of fire; but bringing in for the righteous the times of the kingdom" (Against Heresies, book 5 chapter 30, paragraph 4). That is taken not only from Daniel, but also from Revelation 11 and elsewhere, which PROVES he did not deem it past fulfilled in 70 AD, but looked for a FUTURE fulfillment. Justin Martyr said this: ""But I and others, who are right-minded Christians on all points, are assured that there will be a resurrection of the dead, and a thousand years in Jerusalem, which will then he built, adorned, and enlarged, as the prophets Ezekiel and Isaiah and others declare."
NOw - we can certainly debate whether or not these men were right - but what is absolutely incorrect is your statement that ALL early church fathers believed that the Book of Revelation "clearly spelt out the destruction of the harlot-city of Jerusalem." That is clealry not the case. Only only has to read what they wrote, which I have. Some of them certainly did - but it was certainly not all of them. Several of them made very clear pre-millennialist statements...like Tertullian who said: ""But we do confess that a kingdom is promised to us upon the earth, although before heaven, only in another state of existence; inasmuch as it will be after the resurrection for a thousand years in the divinely-built city of Jerusalem, 'letdown from heaven,' which the apostle also calls 'our mother from above;' and, while declaring that our citizenship is in heaven, he predicts of it that it is really a city in heaven. This both Ezekiel had knowledge of and the Apostle John beheld" (Against Marcion, book 3 chapter 25).
Lactantius very clearly teaches that Christ reigns for 1000 years and Satan is then loosed - then eternity (The Divine Institutes, book 7, chapter 26). It was not a symbolic Book to him, it was a real one...a literal one.