I think Luke 9:27 is a perplexing text that gives preterists the fuel for their beliefs.
There is also this one:
"But when they persecute you in this city, flee ye into another: for verily I say unto you, Ye shall not have gone over the cities of Israel, till the Son of man be come." (Mt 10:23 KJV)
In context, Jesus said he was only sent to the lost sheep of the house of Israel:
"But [Jesus] answered and said, I am not sent but unto the lost sheep of the house of Israel." (Mt 15:24 KJV)
And when he sent forth his disciples, he sent them only to the lost sheep of the house of Israel:
"These twelve Jesus sent forth, and commanded them, saying, Go not into the way of the Gentiles, and into any city of the Samaritans enter ye not: But go rather to the lost sheep of the house of Israel. And as ye go, preach, saying, The kingdom of heaven is at hand. Heal the sick, cleanse the lepers, raise the dead, cast out devils: freely ye have received, freely give." (Mt 10:5-8 KJV)
And after explaining some details of their mission, and obstacles, Jesus made this statement (reposted from above):
"But when they persecute you in this city, flee ye into another: for verily I say unto you, Ye shall not have gone over the cities of Israel, till the Son of man be come." (Mt 10:23 KJV)
It was not until the time Cornelius was converted (after Peter was ordered to "slay and eat" - Acts 10:13) that the disciples added the Gentiles to their mission; but they never stopped looking for the lost sheep until they were dead, or the destruction of Jerusalem. Even Paul, when entering a city, would visit the synagogue first, as risky as that was. He was always seeking to "save some" of "his flesh" (Rom 11:14.)
Philip
Let the Holy Spirit and the Bible itself help you.
Luke 9:27: But I tell you of a truth, there be some standing here, which shall not taste of death, till they see the kingdom of God.
What happened beginning with the very next verse (Luke 9:28-36)?
Some (Peter, James, and John) accompanied Jesus into what is commonly referred to as the "mount of transfiguration." There, they saw that "the appearance of His countenance was altered, and His raiment was white and glistening" (vs. 29). Compare that to the appearance of the risen Jesus in Revelation 1:16, "his countenance was as the sun shining in it strength." They then saw Moses and Elijah who "appeared in glory" (vs. 31) and "they saw his [Jesus'] glory" (vs 32).