The MT and NU texts omit of those who are saved. The term nations (ἔθνη [ethnē] ) denotes the diversity of the redeemed, from every tribe, tongue, people, and nation (Rev. Rev. 5:9+; Rev. 13:7+; Rev. 14:6+). In the place of the sun and moon, the nations walk in the light provided by Gods glory which emanates from the city and illuminates the earth (Rev. Rev. 21:23+; Rev. 22:5+). Questions which arise in our mind concerning the curvature of the earth, how far the glory of God shines upon the earth, and whether there is darkness anywhere upon the earth are not answered in this brief description. The nature of the new heaven and earth could be so radically different from anything we know as to render our questions baseless. Perhaps the Shekinah glory extends its radiant beauty from the city outward over the entire earth.
the kings of the earth shall bring their glory and honor into it
This had already been the experience of the earthly Jerusalem during the Millennial Kingdom (Isa. Isa. 60:3-12; Isa. 66:12). Here is evidence that heaven will be much different than is commonly conceived. These kings are of the earth: having their primary place of activity upon the earth rather than within the city. They bring their glory from outside the city into (εἰς [eis] ) it. The glory and honor of the kings probably describes gifts of value and beauty which are brought as presents of worship to God and the Lamb in the midst of the city. Some have seen this as evidence of two categories of the faithful: those who reside within the city (glorified saints) and those who reside outside the city on the earth (those left living at the end of the Millennial Kingdom).
Those nations, during the Millennium, that walk in the Divine light of the earthly Jerusalem, are transferred to the new earth, to walk in the Heavenly light of the New Jerusalem.1
Is there any way, however, that these could be nations of people still in a natural state (say, like Adam and Eve before the fall) continuing over from the millennium? . . . Admittedly, however, the Scriptures do not deal with this particular subject directly . . . one must certainly be tentative on this point, that this particular group of saints, some from each millennial nation, may have been (like Enoch and Elijah long before) translated to the heavenly Jerusalem still in the flesh. In such a hypothetical situation, they would then be in that state in the city when it descended to the earth. . . . This interpretation of this text, doubtful and fraught with difficulties though it may be, would help in answering certain other questions.2
I . . . hold it to be a necessary and integral part of the Scriptural doctrine of human redemption, that our race, as a self-multiplying order of beings, will never cease either to exist or to possess the earth. . . . Ransomed nations in the flesh are therefore among the occupants of the new earth, and the blessed and happy dwellers in it, as Adam and Eve dwelt in Paradise.3
This is an issue on which the text of Revelation is silent, but there is one . . . theory which seems to satisfy the available criteria best. . . . This opinion holds that the nations are composed of saved people who survive the millennial kingdom without dying and without joining Satans rebellion and who undergo some sort of transformation that suits them for life in the eternal state. They will be like Adam and Eve in the Garden of Eden prior to the Fall (cf. Govett, Seiss). They will be unresurrected human beings who will inhabit the new earth, Paradise restored (Rev. Rev. 22:1-5+), throughout eternity.4
Shall not God then during the Renovation of the Earth by Fire, in some manner, not as yet revealed, take off righteous representatives of the Millennial nations that he purposes to save, and when the earth is again fit to be the abode of men, place them back on the New Earth, that they may increase and multiply and replenish it, as Adam (Gen. Gen. 1:27-28), and Noah (Gen. Gen. 9:1), were told to multiply and replenish the present earth.5This surprising suggestion is not without complications. See commentary on Revelation 22:2.
3 J. A. Seiss, The Apocalypse: Lectures on the Book of Revelation (Grand Rapids, MI: Zondervan Publishing House, 1966), 483, 492.