Then I saw a new heaven and a new earth, for the first heaven and the first earth had passed away, and the sea was no more.

Revelation 21:1

The Old Testament also speaks of new heavens and a new earth:

“For behold, I create new heavens
and a new earth,
and the former things shall not be remembered
or come into mind.
But be glad and rejoice forever
in that which I create;
for behold, I create Jerusalem to be a joy,
and her people to be a gladness.
I will rejoice in Jerusalem
and be glad in my people;
no more shall be heard in it the sound of weeping
and the cry of distress.
No more shall there be in it
an infant who lives but a few days,
or an old man who does not fill out his days,
for the young man shall die a hundred years old,
and the sinner a hundred years old shall be accursed.
They shall build houses and inhabit them;
they shall plant vineyards and eat their fruit.
They shall not build and another inhabit;
they shall not plant and another eat;
for like the days of a tree shall the days of my people be,
and my chosen shall long enjoy the work of their hands.
They shall not labor in vain
or bear children for calamity,
for they shall be the offspring of the blessed of the Lord,
and their descendants with them.
Before they call I will answer;
while they are yet speaking I will hear.
The wolf and the lamb shall graze together;
the lion shall eat straw like the ox,
and dust shall be the serpent's food.
They shall not hurt or destroy
in all my holy mountain,”
says the Lord.

Isaiah 65:17-25

Observation: If this new heaven and new earth is heaven or a time after the end of the world, then why is there still death? (Some of you might wonder why they are building and working. But I would remind you that there was work in the Paradise of Eden before the Fall, so work is not punishment). Why are they having children?
Didn't Jesus say, "For in the resurrection they neither marry nor are given in marriage, but are like angels in heaven"? (Matthew 22:30)

Might this passage refer to this age, before the end of the world? Read Deuteronomy 28. This passage in Isaiah reflects the ultimate fulfillment of those blessings here on earth. Might the new heavens and new earth symbolicly refer to the blessings of salvation?

Something to think about.