John 21:21-23:"Peter seeing him [John] saith to Jesus, Lord, and what shall this man [John] do? Jesus saith unto him, If I will that he tarry [live] till I come, what is that to thee? follow thou me. Then went this saying abroad among the brethren, that that disciple [John] should not die: yet Jesus said not unto him, He shall not die; but, If I will that he tarry [live] till I come [before he dies], what is that to thee?"
NOTE: John (like the Two Witnesses) will prophesy before the "peoples, and nations, and tongues, and kings"; therefore, John matches the criteria to be identified as one of the Two Witnesses.
The Two Witnesses represent two olive trees, the true olive tree (Israel) and the wild olive tree (the New Testament churches) (Rom. 11:4, 24-25). Elijah represents Israel and John represents the New Testament churches.
The Two Witnesses represent two candlesticks (Rev. 11:4). Israel was the light of the Old Testament saints and is represented by Elijah. The church is the light of the New Testament and is represented by John.
Rev. 11:3-4:"And I will give power unto my two witnesses, and they shall prophesy a thousand two hundred and threescore days, clothed in sackcloth. These are the two olive trees, and the two candlesticks standing before the God of the earth."
Rev. 11:7-10:"And when they shall have finished their testimony, the beast that ascendeth out of the bottomless pit shall make war against them, and shall overcome them, and kill them. And their dead bodies shall lie in the street of the great city, which spiritually is called Sodom and Egypt, where also our Lord was crucified. And they of the people and kindreds and tongues and nations shall see their dead bodies three days and an half, and shall not suffer their dead bodies to be put in graves. And they that dwell upon the earth shall rejoice over them, and make merry, and shall send gifts one to another; because these two prophets tormented them that dwelt on the earth."
Rev. 11:11-12:"And after three days and an half the Spirit of life from God entered into them, and they stood upon their feet; and great fear fell upon them which saw them. And they heard a great voice from heaven saying unto them, Come up hither. And they ascended up to heaven in a cloud; and their enemies beheld them. "
NOTE: While John was on the Isle of Patmos, it would have been impossible for him to prophesy to "many peoples, and nations, and tongues, and kings". There is no Scriptural record that John ever did this. But when he comes back (as one of the Two Witnesses), he can prophesy and reach and be seen by the whole world with the media of today (TV and the internet) and possibly even more advanced media of that time.
SUMMARY