The key to this passage is Chronology. Luke's Gospel is written in AD70. The Temple was destroyed in AD70. Did Luke know about the destruction of the Temple or did he not? In my young days it was presumed that he did not know of events on the other side of the world. Today most scholars presume that he did know. This is certainly the more common stance these days. The terrible event had huge effect on the early Christian community. Till this day it has a huge effect on the Jewish community.
The last of the teaching passages of Luke's Gospel refer to the Temple, the end of the world and persecution.
Jesus referred to the destruction of the Temple. "Everything will be destroyed." We know when this event happened. Since then the Jews have no Sacrifice, no priesthood, no Temple. In the time of this Gospel, the event has already happened.
The end of the world is another issue. "When will this happen?" "Take care not to be deceived." "Many will come.... refuse to join them." This section is a mixture of encouragement and eschatology. The Temple has been destroyed and persecution is rampant. The two things have already happened. The end of the world is coming. We can read of the persecutions in the "Acts of the Apostles," Luke's next volume. history has recorded the destruction of the Temple.
Clearly, the end of the world is in the unknown future. Our attitude to this is to be always ready, but never alarmed. Accusations and betrayals and hatred will occur, but we are called to be steadfast. "Your endurance will win you your lives." Jesus' teaching is to be ready for the long haul. The Temple will be destroyed, the persecution will happen, but your endurance will win you eternal life.