The fig tree is a symbol of Old Covenant Israel.
**I will gather them all in, says the LORD: no grapes on the vine, No figs on the fig trees, foliage withered! Why do we remain here? Let us form ranks and enter the walled cities, to perish there; For the LORD has wrought our destruction, he has given us poison to drink, because we have sinned against the LORD. (Jer 8:13-14)
Like grapes in the desert, I found Israel; Like the first fruits of the fig tree in its prime, I considered your fathers. When they came to Baal-peor and consecrated themselves to the Shame, they became as abhorrent as the thing they loved. (Hos 9:10)**
Jesus applied it to his generation.
Seeing a fig tree by the road, he went over to it, but found nothing on it except leaves. And he said to it, “May no fruit ever come from you again.” And immediately the fig tree withered. (Mt 21:19)
"Learn a lesson from the fig tree. When its branch becomes tender and sprouts leaves, you know that summer is near. In the same way, when you see all these things, know that he is near, at the gates. Amen, I say to you, this generation will not pass away until all these things have taken place. (Mt 24:32-34)
The end of the OT age ended with the destruction of the Temple and those in power.
Brother will hand over brother to death, and the father his child; children will rise up against parents and have them put to death. You will be hated by all because of my name, but whoever endures to the end will be saved.When they persecute you in one town, flee to another. Amen, I say to you, you will not finish the towns of Israel before the Son of Man comes. (Mt 10:21-23)
Seven times Jesus said to those in power, “Woe to you, scribes and Pharisees”.
You serpents, you brood of vipers, how can you flee from the judgment of Gehenna? Therefore, behold, I send to you prophets and wise men and scribes; some of them you will kill and crucify, some of them you will scourge in your synagogues and pursue from town to town, so that there may come upon you all the righteous blood shed upon earth, from the righteous blood of Abel to the blood of Zechariah, the son of Barachiah, whom you murdered between the sanctuary and the altar. Amen, I say to you, all these things will come upon this generation. (Mt 23:33-36)
Then Jesus Laments over Jerusalem, and then. . .
Jesus left the temple area and was going away, when his disciples approached him to point out the temple buildings. He said to them in reply, “You see all these things, do you not? Amen, I say to you, there will not be left here a stone upon another stone that will not be thrown down.” As he was sitting on the Mount of Olives, the disciples approached him privately and said, “Tell us, when will this happen, and what sign will there be of your coming, and of the end of the age?” (Mt 24:1-3)
The end of the age happened within 40 years. He was talking to those who were listening at the time.