Brother Robycop, the discussion Jesus was having with the disciples in Matthew 16 had nothing to do with the transfiguaration miracle. That is conjecture on your part. Now I see how dispensational futurists are explaining Matthew 16: 27-28.
Verse 21 states: From that time on Jesus began to explain to his disciples that he must go to Jerusalem and suffer many things at the hands of the elders, the chief priests and the teachers of the law, and that he must be killed and on the third day be raised to life." I don't see any mention of Elijah or Moses. The message was for his disciples! Here is the rest of that section of Matthew 16 so everyone can see the context of whom this message was intended for:
24 Then Jesus said to his disciples, “Whoever wants to be my disciple must deny themselves and take up their cross and follow me. 25 For whoever wants to save their lifef]">[f] will lose it, but whoever loses their life for me will find it. 26 What good will it be for someone to gain the whole world, yet forfeit their soul? Or what can anyone give in exchange for their soul? 27 For the Son of Man is going to come(parousia) in his Father’s glory with his angels, and then he will reward each person according to what they have done. 28 “Truly I tell you, some who are standing here will not taste death before they see the Son of Man coming in his kingdom.”
Seeing as how Jesus has NOT yet returned, how else can you explain it?