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Dear Reader,
Its reasonable to raise the concern that all Scripture/Prophecy would need to be fulfilled by 70AD, especially since several good men among modern Preterists since Max King's 1970's-era milestone, Spirit of Prophecy , have given attractive arguments for such a conclusion. But it must be remembered that they all owe an even greater debt to James S. Russell's 19th century mountain-moving tome, The Parousia: A Critical Inquiry into the New Testament Doctrine of Our Lord's Second Coming , which centers fulfillment of prophecy around the "Day of the Lord" rather than any date. Russell is among the greatest, if not the first, to prove conclusively that the "Day of the Lord" dawns with Christ's Return circa 70AD. Nobody gets a 70AD Return of Christ without the Bible skills championed by James Stuart Russell. Nobody.
As you've inescapably concluded by now, my approach can be fairly introduced by this soundbite:
Eschatology, (the explanation of last things), revolves around "The Day of the Lord" rather than the date "70AD."
When we regard 2 Peter 3:8 (and Ps 90:4) to suggest that Rev 20's "The 1,000 Years" = "The Day of the Lord" of which the Law & Prophets and the NT speak,
and we recall that the focus about which eschatology revolves is "The Day of the Lord" rather than the date "70A.D.,"
we come to realize that all the Law & Prophets find their fulfillment with "The Day of the Lord," the beginning thereof circa 70A.D.
The above are just reiterations of what I have been saying all along. You deserve a tailor made answer to your concern here, though. I generally prefer to make my own such arguments, but I'm pressed for time right now and believe you also deserve a prompt reply. Please accept this link for now to Duncan McKenzies' approach in the which I find much merit. (Though Duncan also makes some Partial-Preterist statements with which I disagree. But this is part of the beauty of my approach, as I see it, it satisfies the valid concerns of Partial-Preterists while coming to the triumphant conclusions in which Full Preterism rejoices: there is no end, there is no fatalistic sentence upon past generations dooming our future, Tommorrow is a blank page to be co-authored together by God & the Blood-bought, Redeemed: Tommorrow is determined by what we do with Jesus Today, not by the failures of generations long since silenced. May the view I have been presenting serve as a bridge of understanding between Partial & Full Preterists that brings a more united front in presenting the glorious reality that Jesus is Back and living among us. The shout of a king is among the His Chosen People, the Church!). I will try to compose a fresh, personal answer to this claim that all prophecy be fulfilled by the 1st century when I find time.
May God bless through Jesus Christ our Teacher all who read, may He open our eyes to see wonderful things in His Word, granting us the spirit of wisdom and revelation in the knowledge of Him and may He grant us the grace to grow in the knowledge that does not puff up, but rather, multiplies grace & peace. Amen.
BONUS QUESTION:
How might this passage have possibly been fulfilled by A.D.70?

Isa 65:20-23
20 "No longer will there be in it an infant who lives but a few days,
Or an old man who does not live out his days;
For the youth will die at the age of one hundred
And the one who does not reach the age of one hundred
Shall be thought accursed.

21 "And they shall build houses and inhabit them;
They shall also plant vineyards and eat their fruit.
22 "They shall not build, and another inhabit,
They shall not plant, and another eat;
For as the lifetime of a tree, so shall be the days of My people,
And My chosen ones shall wear out the work of their hands.
23 "They shall not labor in vain,
Or bear children for calamity;
For they are the offspring of those blessed by the LORD,
And their descendants with them.
NASB

Observations:
1) People are working with their hands and they live to outlast the things they build.
2) People are being born and dying but living "as the days of a tree," which is not forever, but indeed a blessed, long time.
(There are sequoias calculated to live 2,000 years, redwoods up to 800 years, like Adam who lived 935 years).
3) Some people among them are regarded as "accursed," ie, under God's disapproval. They live less than 100 years.
4) It is considered a tragic loss to die in one's youth at age 100.
And this is love, that we walk after Christ's commandments ~2 John 6