Although it seems out of place in the setting, Jesus was not speaking only to those who were with him, but also to all of us who would come later in time and hear his answer through the transmission of its witnesses. This is revealed by the breadth of his answer. John was the only one of that bunch that lived more than another 50 years (at least according to tradition), and the scope of Jesus' answer is actually much longer than that when it’s carefully examined. In fact, it is so broad that we are encompassed within its detail today, and in a very real sense, those that were hearing him were stand-ins for all of us.
Jesus described that scope (v. 4-8) as encompassing wars, famines, earthquakes and false Messiahs (all in the plural). However, Jesus stated that such, even in the plural, would not be a reason for any eschatological alarms to be sounded. The end was not yet, even after a multiplication of such things. In his account, Luke adds pestilence, terrors and signs in the heavens to the mix, all in the plural as well. We have been seeing these things throughout history, and are still seeing those things today, yet they still should not be alarming because they're not the telling sign of the end of the age.
Furthermore, the occurrences of these signs are represented as akin to the progression of labor, but just the beginning of it (v. 8). Labor starts slowly and builds in a cyclical pattern of increasing intensity, and culminates in a grand conclusion. The process can be quite lengthy, a few hours if one is lucky, over a day if not. A proper reading of these signs must incorporate a lengthy process (i.e, labor) of repetitively building events (wars, famines, earthquakes, false messiahs) that themselves take a lengthy time to develop, and that's just the start. Clearly, Jesus envisioned a very a long time in his answer.
He also spoke of false prophets arising and leading many astray (v. 11). History has seen its share of those, although it seems to me, the most significant (e.g., Muhammed, Joseph Smith and Charles Taze Russell) arose long after the Temple was destroyed. If the termination of the prophesy is the end of the age and Jesus' return, these false prophets, as well as historical false messiahs, such as Bar Kochba, Menachem Schneerson, and even Sun Myung Moon would have been in view by Jesus as he spoke about such, such a long time ago.
In these issues alone, I have already demonstrated the difficulty of compressing all of these signs into the short span of time before 70 CE, but let us remember that the terminus of the prophetic answer was the end of age and Jesus' return. This is certainly reinforced by Jesus tying the fulfillment of the Great Commission (v.14) to his answer. Even now, we're only just reaching the point where this sign is even remotely fulfilled and the end will not come before it is accomplished. Preterism, it seems clear to me, is a non-starter in interpreting Matthew 24.
Jesus also referenced the desolation mentioned by Daniel (v. 15) as a sign. At the time Jesus spoke this, Antiochus and the Maccabees were a well-known and understood aspect of history, and yet Jesus spoke of Daniel's desolation as happening in the future. As Jesus would have used the term, it referred to an idol being placed in the Temple and the altar being desecrated. Jesus was saying that Antiochus' actions were not the ultimate fulfillment of Daniel's prophecy, but that it would be fulfilled as the most salient sign of the imminent end of the age.
History tells us that Rome's actions at the Temple in 70 CE were not the fulfillment of Daniel's prophecy either, because they do not fit the bill. Whereas the Romans burned the place, killed its defenders on its grounds and dismantled it, they did not set up Daniel’s desolation. Hadrian's efforts in 130 CE to put a Roman face on a formerly Jewish city weren't even close to fulfilling Jesus' reference to Daniel, and nothing has occurred throughout the rest of history that is even remotely similar to Daniel's description. That means that the Abomination of Desolation, as cited by Christ, is something yet to happen.
It is common among naysayers, and preterists too, to say that Jesus and his first followers anticipated the end occurring quickly, within their lifetimes at most. Jerusalem was destroyed in 70 CE, and they see that event as the scope of the Olivet Discourse. Preterists see it as fulfilled, the unbelieving see it as reportage after the fact, but either way, the events of 70 CE don’t line up with the facts as Jesus stated them. Neither viewpoint can be true!
What is true is that the Gospel has not yet to be proclaimed to all nations, the desolation spoken of by Daniel has not yet occurred, and Jesus has not yet appeared. So the age has not ended and this prophetic discourse, therefore, is still in force.