Matthew 24 can only be understood when synced with Luke 17 and 21

According to tradition Mark gathered quotes and events from Jesus when Peter spoke. As such and because Mark was not a witness himself of these events, the result is not very chronological.

Nevertheless Mark did a good job, because Matthew who was a witness follows him to a very large extent, but he did not change a lot regarding to the chronology either.

But this was confusing at some points, therefor Luke says in the first four verses of his report, that he went through the previous written material (as well as adding new things from witnesses) to put it into a consistent and chronological order.

One of the problems with Mark is his chapter 13 and Matthew's chapter 24. Quotes from Jesus about the destruction of Jerusalem and of the second coming of Christ were mixed together. Therefore Luke splits those into two. Chapter 17 is only about the coming of Christ and chapter 21 first is about the destruction of Jerusalem and then switches to Jesus' second coming.

In order to understand quotes in Matthew 24 correctly, we first HAVE to synchronize them with Luke 17 and 21. After we have done that, we know whether the quotes were about the destruction of Jerusalem or Jesus' second coming, because from Luke that is a lot clearer.

Then we will get this:

	Matthew 24	Luke 21
Introduction	verses 1-3	verses 5-7
general period after the destruction of Jerusalem	4-8	8-10
prelude to the destruction of Jerusalem	9-10	12-19
signs before Jesus' coming	11-14	no parallel texts
destruction of Jerusalem, start of Roman exile	15-16; 19-22	20-24
Jesus' second coming	17; 23-28	placed in Luke 17
signs (Israel goes into exile)	29	25-26
Jesus' second coming	30-36	27-33
Jesus' second coming	37-41	placed in Luke 17
Jesus' second coming	42-51	34-36

Some conclusions we can draw from this are:

1. The Abomination of Desolation from Daniel is about the destruction of Jerusalem (Matthew 24:15, Luke 21:20). Also see this blog. 
2. Matthew 24:34 is about the second coming of Jesus. The word genea, translated with 'generation' can also mean family or race. See biblehub. Thus we should understand this verse as: the Jews will not cease to exist before Jesus will come back. That makes sense, because with the destruction of Jerusalem and the temple and the Jews going into exile for almost 2000 years, one would expect a nation to be completely annihilated. Jesus says: THAT will not happen to the Jews, they will still exist when I come back.