Matthew 24:32-35 (ESV)
"From the fig tree learn its lesson: as soon as its branch becomes tender and puts out its leaves, you know that summer is near.  So also, when you see all these things, you know that he is near, at the very gates.  Truly, I say to you, this generation will not pass away until all these things take place.  Heaven and earth will pass away, but my words will not pass away.
“This generation” generation can have many different meanings, but generally it means a period of time encompassing that in which a person is born and dies. Jesus himself is saying this just days before his death. So if we are to interpret generation as generation, and not as age, being as the text gives us no reason to interpret as age, and not as generation, then we are left with these things happening by A.D. 100. That is saying a generation is about 70 years.
And of course they all do! The temple is destroyed, false prophets do come. What hasn’t happened is Christ has not returned on clouds with Angels to gather the elect. One could make the argument that this bit about sun and moon happened with the darkness over the land at Christ’s death, though it would in the end only be a partial fulfillment of the prophecy, just as Christ’s resurrection was a partial fulfillment of the prophecy of the resurrection of the dead in general. It is a necessary partial fulfillment that sets the stage for the full fulfillment. But that is really at the core, for the disciples, and Jews in general, the resurrection of even just one person from the dead, was an indication that the end had come. This is the heart of the gospel which is thoroughly eschatological. It for this reason that any theology that puts the end off to another time, and does not see today and yesterday and the last 2000 years of history as the end times, seeks to give a different gospel, even as it robs the gospel of the glory of the good news that it is.
One could though, understand that Jesus speaks of the things that need to happen before he can return, and those things that happen in conjunction, simultaneously with his return. And this is the option that I go with. The sun going dark, and the moon turning to blood, the stars shaking etc, will happen directly with Christ’s return, the other things of which Christ speaks will happen within this generation, so that even that generation can expect the return of Christ.
And this is the whole program of Matthew 24, he doesn’t want you to know when he is coming back. He gives some information so that we will know what the end times will be like, so the disciples will be prepared to face those things, but not to scare people about the coming of Christ, and not to give them some code so that we can figure out when he is returning. That these things will happen in that generation does not mean that they will cease with that generation either. Of course the temple can only be destroyed once, but the false prophets, wars, rumors, etc. are on going in the history of the world, and reminders to Christians that Christ’s return is imminent!