Mark 13:30

“Truly I say to you, this generation will not pass away until all these things are accomplished.”

Again ‘these things' refer to the signs preparatory to His coming, the world troubles, the preaching, the persecution, the destruction of the Temple, distress of nations. And they did all happen to sufficient extent within that generation. Those who seek to turn all this into a prophecy of the end times take ‘generation' either as referring to the generation which sees the final signs (but for that we would have expected him to write ‘that generation'), or translate as ‘this race' meaning the Jews, but both are unnatural interpretations and a little forced. (Indeed we may ask ‘which race?', for none has been mentioned in the context). The natural reference is to the generation of Jesus' day.

For the significance of ‘these things' see Mark 13:4, where it primarily refers to the destruction of the Temple, but also incorporating Mark 13:14 which are prior to that, and Mark 13:5 where it refers to the wars among nations and accompanying natural disasters. As Jesus states quite clearly that He did not know the time of His coming He could hardly have rationally included that, and anyway ‘these things' are indicators of the imminence of His coming (Mark 13:29) and cannot therefore include that coming itself.