Revelation 22:6 And he said unto me, These sayings are faithful and true: and the Lord God of the holy prophets sent his angel to shew unto his servants the things which must shortly be done.
7 Behold, I come quickly: blessed is he that keepeth the sayings of the prophecy of this book.
8 And I John saw these things, and heard them. And when I had heard and seen, I fell down to worship before the feet of the angel which shewed me these things.
10 And he saith unto me, Seal not the sayings of the prophecy of this book: for the time is at hand.
If we then factor the following in, should we not assume that these things span multiple generations?
Revelation 1:9 I John, who also am your brother, and companion in tribulation, and in the kingdom and patience of Jesus Christ, was in the isle that is called Patmos, for the word of God, and for the testimony of Jesus Christ.
Revelation 20:10 And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever.
11 And I saw a great white throne, and him that sat on it, from whose face the earth and the heaven fled away; and there was found no place for them.
12 And I saw the dead, small and great, stand before God; and the books were opened: and another book was opened, which is the book of life: and the dead were judged out of those things which were written in the books, according to their works.
13 And the sea gave up the dead which were in it; and death and hell delivered up the dead which were in them: and they were judged every man according to their works.
14 And death and hell were cast into the lake of fire. This is the second death.
15 And whosoever was not found written in the book of life was cast into the lake of fire.
Unless one is a full Preterist, no one is going to argue that Revelation 20:10-15 has already been fulfilled, that is was fulfilled in the 1st century. Only a full Preterist could argue something such as that.
While Revelation 22:10---for the time is at hand---can obviously be applied to the period of time involving Revelation 1:9, how can it in the same manner be applied to what is recorded in Revelation 20:10-15? Revelation 1:9 is meaning 2000 years ago. Revelation 20:10-15 hasn't even been fulfilled yet. Shouldn't this at least tell us that the time was at hand 2000 years ago, and that it continues to be at hand until the end of this age involving Christ's bodily return?
Something to note is what John said in Revelation 1:9---who also am your brother, and companion in tribulation---for the word of God, and for the testimony of Jesus Christ.
Compare that with---
and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God(Revelation 20:4)
And with this as well---
And when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held(Revelation 6:9)
But that only takes into account all of the saints who were already martyred before they are told to rest yet a little season, until their fellowservants also and their brethren, that should be killed as they were, should be fulfilled(Revelation 6:11)
It seems to me then, the fact John indicated the beast was 'is not' at the time, that it was to ascend out of the pit in the future, that this means John would also be among the ones crying out for vengeance in Revelation 6:9, that he was martyred prior to the time of the little season meant in Revelation 6:11. Keeping in mind that he was eventually martyred, obviously meaning after he saw any of these visions.
Which means that a little season needs to be fulfilled first, something that never happened in John's day. Which then tells us what I am already arguing, that the time is at hand, and that it began in the first century and continues to the end of this age.
What the OP is arguing in regards to comparing Daniel 8 to Revelation, this is basically irrelevant for the following reasons. The time wasn't at hand in Daniel's day, involving any of those visions, but would be at hand in John's day involving the visions he saw. But that still doesn't mean every single vision John saw, that they all involved only his day and time. The fact a little season has to be entirely fulfilled first, meaning once the martyrs under the altar cry out for vengeance, this alone tells us that the book of Revelation is involving events that began in the first century and continue until the literal end of this age. What about the ones martyred during the little season? When does God enact vengeance for them if He already allegedly did that pertaining to 70 AD or whatever?
And that some of Revelation is even involving events beyond the end of this age, such as Revelation 21-22, and that Premils also argue, so is the thousand years. But since the latter is debatable, one can't use that as undeniable proof. Maybe Revelation 21-22 is debatable as well since some Preterists don't interpret those 2 chapters in the same manner as some of the rest of us do.