It is significant that Matthew, Mark, and Luke record the Transfiguration immediately following this prediction found in Mark 9:1. There is no break in the narrative-no chapter or verse division in the Greek original- and furthermore all three mention the fact that the Transfiguration occurred about a week after this statement, implying that the event was the fulfillment of the prediction.
The connection between the two sections of narrative seems to preclude the possibility that Jesus here referred to anything but the Transfiguration, which was a miniature demonstration of the kingdom of glory. Undoubtedly, Peter understood this to be case as you can see in 2 Peter 1:16-18.
The people living to see a miniature example of the kingdom of God coming were Peter, James, and John. The disciples recognized the heavenly visitants either from their conversation or by divine illumination. Moses was the great deliverer, lawgiver, and founder of the Hebrew nation, and Elijah the one who saved it in a time of great apostasy and crisis. Here were living representatives to bear witness to the divinity of Jesus, even as “Moses and all the prophets,” through their written records, had testified of Him (Luke 24:44).
It is important to note that regarding both Elijah (2 Kings 2:11, 12) and Moses (Jude 9) the Scriptures record the fact that the one was translated to heaven without seeing death and the other raised from the dead. The fact that Moses and Elijah appeared with Christ at this time is therefore not to be taken to prove that all the righteous dead are in heaven. These two, one raised from the dead and the other translated without seeing death, appeared with Jesus, as a type of the glorious kingdom in which the ransomed of all ages will be with Him in glory (Matt. 25:31; Col. 3:4; 1 Thess. 4:16, 17).
This was a miniature example of how the Jesus’ second coming would be like and these three disciples got to see it and hence they fulfilled the prediction ‘that some that stand here shall not taste death till they have seen the kingdom of God come’.
In His service,