Matthew 24, Mark 13 & Luke 21 all speak of the events surrounding the destruction of Jerusalem some 40 years later. Within that generation that received the discourse.
“When they persecute you in one town, flee to the next; for truly I tell you, you will not have gone through all the towns of Israel before the Son of Man comes.” Matthew 10:23, NRSV
“But truly I tell you, there are some standing here who will not taste death before they see the kingdom of God.” Luke 9:27, NRSV
“ for these are days of vengeance, as a fulfillment of all that is written.” Luke 21:22, NRSV
“Truly I tell you, there are some standing here who will not taste death before they see the Son of Man coming in his kingdom.” Matthew 16:28, NRSV
“Truly I tell you, this generation will not pass away until all these things have taken place.” Matthew 24:34, NRSV