Great point.
I think we lose perspective sometimes by not realizing that less than 100 generations have passed since the days of Jesus Christ.
"This generation shall not pass" clearly is speaking to the current generation to whom it was written.
And three of the Gospel writers wrote the verse exactly the same...
"Verily I say unto you, that this generation shall not pass, till all these things be done." -- Mark 13:30 "Verily I say unto you, this generation shall not pass away, till all be fulfilled." -- Luke 21:32"Verily I say unto you, this generation shall not pass, till all these things be fulfilled." -- Matthew 24:34
He's referring to that generation at the time of the end. It's clear as a bell to me. Other considerations (such as the extent of the prophecies He was just talking about) clearly indicate to me that He's talking about a different "day and hour" when these things will happen.
32 "Now learn this lesson from the fig tree: As soon as its twigs get tender and its leaves come out, you know that summer is near. 33 Even so, when you see all these things, you know that it is near, right at the door. 34 I tell you the truth, this generation will certainly not pass away until all these things have happened. 35 Heaven and earth will pass away, but my words will never pass away. 36 "No one knows about that day or hour, not even the angels in heaven, nor the Son, but only the Father. 37 As it was in the days of Noah, so it will be at the coming of the Son of Man. 38 For in the days before the flood, people were eating and drinking, marrying and giving in marriage, up to the day Noah entered the ark; 39 and they knew nothing about what would happen until the flood came and took them all away. That is how it will be at the coming of the Son of Man. 40 Two men will be in the field; one will be taken and the other left. 41 Two women will be grinding with a hand mill; one will be taken and the other left. 42 "Therefore keep watch, because you do not know on what day your Lord will come. 43 But understand this: If the owner of the house had known at what time of night the thief was coming, he would have kept watch and would not have let his house be broken into. 44 So you also must be ready, because the Son of Man will come at an hour when you do not expect him. 45 "Who then is the faithful and wise servant, whom the master has put in charge of the servants in his household to give them their food at the proper time? 46 It will be good for that servant whose master finds him doing so when he returns. 47 I tell you the truth, he will put him in charge of all his possessions. 48 But suppose that servant is wicked and says to himself, 'My master is staying away a long time,' 49 and he then begins to beat his fellow servants and to eat and drink with drunkards. 50 The master of that servant will come on a day when he does not expect him and at an hour he is not aware of. 51 He will cut him to pieces and assign him a place with the hypocrites, where there will be weeping and gnashing of teeth. 29 "Immediately after the distress of those days "'the sun will be darkened, and the moon will not give its light; the stars will fall from the sky, and the heavenly bodies will be shaken.' 30 "At that time the sign of the Son of Man will appear in the sky, and all the nations of the earth will mourn. They will see the Son of Man coming on the clouds of the sky, with power and great glory. 31 And he will send his angels with a loud trumpet call, and they will gather his elect from the four winds, from one end of the heavens to the other.
Well they did write exactly "the same".
FWIW the Greek word for "this" which is used there can also be translated as "the same" Mt24:13. So it clearly can be translated as "the same generation" which sees all these things shall not pass away until all if fulfilled.
Since all that which preceeded the statement was clearly not fulfilled in 70AD we can therefore conclude that the reference was not to the 70AD generation, but the same generation that would see all these things fulfilled.