In my judgment (For what it's worth) as an amillenialist (who thinks Jesus answers two questions of the disciples by dividing them: the destruction of the Temple/Jerusalem, and the end of the world; which were combined in their minds)
there is simply a lack of connection for the average American reader between the language of Jesus and the language of Jesus' Scripture, the OT. Consequently, when the words are read, "...see the Son of Man coming in the clouds," the only way that language is intelligible to them is that this is primarily visual. Up in the sky, billowing clouds--white, grey, smoky, colorific--parting to reveal the Lord descending in his flesh. This "seeing" is just ocular, and they do not incorporate the notion of "interpretation" with the term. Too bad.
But for the disciples, who may have been expected to know what the prophets sounded like, they had texts like Isaiah 19:1,"An oracle concerning Egypt. Behold, the LORD is riding on a swift cloud and comes to Egypt; and the idols of Egypt will tremble at his presence, and the heart of the Egyptians will melt within them."
Such is the language of judgment. Nahum 1:3, "...the LORD hath his way in the whirlwind and in the storm, and the clouds are the dust of his feet." Clouds are often associated with the presence of God, Ps.97:2, "Clouds and darkness are round about him: righteousness and judgment are the habitation of his throne;" Ex.24:!6, "And the glory of the LORD abode upon mount Sinai, and the cloud covered it six days: and the seventh day he called unto Moses out of the midst of the cloud."
While it is later promised that the Lord will return as he departed, bodily Act.1:11; with audibles and visuals, 1Ths.4:16-17; again with judgment language, "Behold, he cometh with clouds; and every eye shall see him, and they also which pierced him: and all kindreds of the earth shall wail because of him," Rev.1:7;--yet, it is false to reduce phrasing found in Mk13:26 to a visual aspect.
Is.19:1 does not teach the Egyptians SAW Jehovah's form, or even a literal cloud that scooted around the land, but hid (or was) the theophany. What is manifest to the mind and senses, through the tokens of judgment in signs and agents, is the reality that Jehovah God brings the judgment.
Jesus' point in the Olivet discourse is of the very same kind. When the physical Temple is overthrown, it is to be a sign that Jesus himself--as God--comes as of old to answer those who did him wrong, who rejected his claims upon the throne and hearts of Israel, and who did not repent unto the last opportunity.
It is truly significant that we appreciate this point. Jesus HIMSELF DESTROYED THE (NOW) FALSE TEMPLE. It is one major reason why we can be sure that nothing but a possible counterfeit will ever be erected again. The meaning of the Temple was transferred decisively to his own body, Jn.2:21, a body incidentally that was destroyed by the caretakers of the marble edifice. So, when that body was raised only three days later... is it any wonder that he promises to return the slight with prejudice?
The end of the OT era is marked by the A.D.67-70 judgments. They are also harbingers of the end of the world, when the Son returns to Judge and to renovate Creation and Kingdom. So, there is a tie between the answers Jesus gives the disciples.
