The old heaven and earth was the temple.
Heaven and earth shall pass away, but my words shall not pass away. Matthew 24:35 KJV
According to Josephus , the Jews at that time considered the temple to be heaven (Holy of Holies) and earth (Outer Temple). Their whole lives revolved around the Temple. So, when Jesus said the above verse, the Jews knew exactly what He was referring to. It is not the physical heaven and earth. You talk about audience relevance: Well here you are!
The Jews Paul wrote to in 1Co knew also what he was saying when he wrote:
Know ye not that ye are the temple of God, and that the Spirit of God dwelleth in you? 1 Corinthians 3:16 KJV
He said this a few years of the temple and the destruction of Jerusalem. So, those Jewish Christians understood this.
Now to Revelation:
And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away, and there was no more sea. Revelation 21:1 KJV
I have a question. Please explain if the new heaven and new earth are physical and sin has been destroyed, why are they still ungodly people in existence?
He that is unjust, let him be unjust still: and he which is filthy, let him be filthy still: and he that is righteous, let him be righteous still: and he that is holy, let him be holy still. Revelation 22:11 KJV
14 Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city. 15 For without are dogs, and sorcerers, and whoremongers, and murderers, and idolaters, and whosoever loveth and maketh a lie. Revelation 22:14-15 KJV
“…may enter in through the gates into the city.” This is the Kingdom of God, the new Jerusalem, which is now! If you know Jesus, you have the right to eat from the Tree of Life and enter through the gates! THIS IS GOOD NEWS!
“For without… ” These are the ones who cannot enter into the new Jerusalem because they did not receive Jesus. NOT GOOD!
This is now! Not sometime in the future! If not, why are sinners still on this so-called physical earth!?
The kingdom of God is not only in you, it is in your midst (Luke 17:21). The Greek word for ‘within’ is ‘en-tos’; within you, i.e. in the midst.
The kingdom of God is all around us, which has many mansions (those in Christ) and we are to compel those who are without to come in.
For my responses to the other, please see my other post. I don’t know how to get the link to it.
 “However, this proportion of the measures of the tabernacle proved to be an imitation of the system of the world; for that third part thereof which was within the four pillars, to which the priests were not admitted, is, as it were, a heaven peculiar to God. But the space of the twenty cubits, is, as it were, sea and land, on which men live, and so this part is peculiar to the priests only.” — Josephus-Works: Josephus AOJ – Book 3, Chapter 6