All kings shall fall down before - They shall reverence him on account of his great wisdom, riches, etc.

All nations shalt serve him - All the surrounding nations. This and the preceding verses are fully explained by 1 Kings 10:23-25 : "King Solomon exceeded all the kings of the earth for riches and for wisdom. And all the earth sought unto Solomon to hear his wisdom. And they brought every man his present, vessels of silver, and vessels of gold, and garments and armor, and spices, horses and mules a rate year by year." If we take these expressions to mean literally all the habitable globe, then they cannot be applied to Solomon; but if we take them as they are most evidently used by the sacred writer, then they are literally true. When all the earth shall be brought to receive the Gospel of Christ, then they may be applied to him.

all kings

Psalm 2:10-12 Be wise now therefore, O you kings: be instructed, you judges of the earth...

Psalm 138:4,5 All the kings of the earth shall praise you, O LORD, when they hear the words of your mouth...

Isaiah 49:22,23 Thus said the Lord GOD, Behold, I will lift up my hand to the Gentiles, and set up my standard to the people...

Revelation 11:15 And the seventh angel sounded; and there were great voices in heaven, saying...

Revelation 17:14 These shall make war with the Lamb, and the Lamb shall overcome them: for he is Lord of lords, and King of kings...

Revelation 21:24,26 And the nations of them which are saved shall walk in the light of it: and the kings of the earth do bring their glory and honor into it...

all nations

Psalm 86:9 All nations whom you have made shall come and worship before you, O Lord; and shall glorify your name.

Isaiah 11:9 They shall not hurt nor destroy in all my holy mountain: for the earth shall be full of the knowledge of the LORD...

Isaiah 54:5 For your Maker is your husband; the LORD of hosts is his name; and your Redeemer the Holy One of Israel...

Romans 11:25 For I would not, brothers, that you should be ignorant of this mystery, lest you should be wise in your own conceits...

Revelation 20:1-6 And I saw an angel come down from heaven, having the key of the bottomless pit and a great chain in his hand...

Jesus --"All Blessing and all Blest"
THERE are many famous names in human history; but many of them are connected with deeds which have brought no blessing upon mankind. To bless, and to be blessed, is the noblest sort of fame; and yet how few have thought it worth the seeking! Full many a name in the roll of fame has been written there with a finger dipped in blood. It would seem as if men loved those most who have killed the most of them. They call those greatest who have been the greatest cutthroats. They make their greatest illuminations …
Charles Haddon Spurgeon—Spurgeon's Sermons Volume 37: 1891

The Millennium in Relation to Sin.
In spite of the fact that Satan will have been removed from the earth, and that Christ reigns in person over it, yet conditions here will not be perfect even in the Millennium. Unregenerate human nature will remain unchanged. Sin will still be present, though much of its outward manifestation will be restrained. Discontent and wickedness will not be eradicated from the hearts of men, but will be kept beneath the surface by means of the Iron Rod. Multitudes will yield to Christ nothing but a "feigned …
Arthur W. Pink—The Redeemer's Return

The Millennium in Relation to the World.
The Millennium will be the time, when, instead of Satan being the world's "Prince," the Christ of God shall be its King. The form of His government will be theocratic not democratic--"And the Lord shall be King over all the earth" (Zech. 14:9). The scope or range of His government will be world-wide. All nations will be subject to His rule, and the uttermost parts of the earth shall be possessed by Him. "He shall have dominion from sea to sea, and from the river unto the ends of the earth. They that …
Arthur W. Pink—The Redeemer's Return