With the verse that follows, a new pericope begins. From Matthew 24:45 to Matthew 25:30 the Lord told three parables to illustrate what He had spoken before. People would be watchful and endure until the end in the period preceding His coming, because they do not know when the Son of Man will come. His coming here concerns one specific moment, which means the end of the present aeon and the beginning of a new aeon. People must be ready for that event, because then the Kingdom will dawn and if they are not ready, they will not enter the Kingdom.
31 And when the Son of Man shall come in His glory, and all the holy messengers with Him, then He will sit on the throne of His glory.
Ben Adam
We have already looked at the title the Son of Man. This is not just a reference to the incarnation of the Lord Jesus, but an honorary title. He is the Ben Adam (Ps.8:5), the heir of Adam, who would rule over all creation (Gen.1:28).
At the moment described here, the Lord comes to take up this position and the Kingdom is established worldwide. As the Ben Adam He will rule over all creation and reign as King (1 Cor.15:25). The rule of the Messiah will not only include His reign in the future aeon, but also in the aeon that comes after that, the aeon of aeons (Heb.1:8; Eph.3:21): the age of the new heaven and new earth (Rev.21:1).
until
His rule lasts until He has subdued all enemies. The last enemy is death, and it will be destroyed at the end of the aeon. Then He will hand over the kingdom to God the Father (1 Cor. 15:24-28). Here in Matthew 25 it is the nations that are subdued, as we will see in the next verse.
the seventh trumpet
The moment described in Matthew 25:31 coincides with the seventh trumpet in the book of Revelation. It is the moment when the mystery, or the hiddenness, is completely fulfilled and the Kingdom is established worldwide.
Revelation 10
7 But in the days of the voice of the seventh messenger, when he shall sound the trumpet, then should the mystery of God be finished (…)
Revelation 11
15 And the seventh messenger sounded: and there were great voices heard in heaven, saying, The kingdom of this world is become the kingdom of our Lord, and of his Christ; and he shall reign for the aeons of the aeons. Amen!
two aeons
This moment is described in Matthew 25:31 as the coming of the Son of man in His glory. The mystery is fulfilled and the Kingdom is revealed over all nations and over the whole earth. The whole world is then the Kingdom of the Messiah. Two great aeons dawn. First, the future aeon of the thousand years, which is yet surpassed in glory by the aeon that comes after it: the aeon of the new heaven and earth.