When Bible prophecy speaks of “this generation,” it is necessary to consider the context to determine what generation is meant. Jesus Christ, when denouncing the Jewish religious leaders, concluded by saying: “Truly I say to you, All these things will come upon this generation.” History recounts that about 37 years later (in 70 C.E.) that contemporary generation personally experienced the destruction of Jerusalem, as foretold.—Mt 23:36.
Later that same day, Jesus again used practically the same words, saying: “Truly I say to you that this generation will by no means pass away until all these things occur.” (Mt 24:34) In this instance, Jesus was answering a question regarding the desolation of Jerusalem and its temple as well as regarding the sign of his presence and of the conclusion of the system of things. So his comment about “this generation” logically had an application down to 70 C.E. However, he was also using the word “generation” with reference to humans whose lives would in some way be associated with the foretold events during his presence.—Mt 24.
Okay. One can't trust anything Matthew, Mark, Luke, or John say.Blame the author of Matthew.