I tell you truly," he said, to them, "there are some of those standing here who will not taste death till they see the coming of God's Reign with power."
what we do see is Jesus who was put lower than the angels for a little while to suffer death, and who has been crowned with glory and honour that by God's grace he might taste death for everyone.
Then the Sign of the Son of man will appear in heaven; then all tribes on earth will wail, they will see the Son of man coming on the clouds of heaven with great power and glory.
This started the report among the brotherhood that the said disciple was not to die. Jesus, however, did not say he was not to die; what he said was, "If I choose that he should survive till I come back, what does that matter to you?"