Not all of the Book of Revelation has happened yet, but I believe most of it has. Jesus returns only a Second time, never a third. Besides, Revelation (while truth) is written in apocalyptic metaphors. Clouds were associated in the OT with divine activity: they symbolised God's power and majesty. Here, at Jesus' Second Coming, they too announce God's power and majesty.
Hello Tintin,
The book of Revelation is divided into three parts when he told John to write 1) what you have seen, 2) what is now and 3) what will take place later.
What you have seen: Everything that John wrote about from Rev.1:19
What is now: Is represented by the letters to the seven churches, which represents the entire church period, which is the now.
What will take place later: Everything that takes place after the now i.e. everything that takes place after the church period. Therefore, nothing from Rev.4 has yet taken place.
This is why we do not find the word Ekklesia/Church after the end of chapter 3 and that because the church is gone. Also, we have yet to see the opening of the 1st seal, which represents the revealing of the Antichrist, who is a counterfeit of the rider on the white horse found in Rev.19:11-21. Those who are here during the time of God's wrath will know when the 1st seal is opened when that antichrist makes his seven year covenant with Israel, which initiates that last seven years. Furthermore, none of the plagues of wrath have yet begun and will not until the Lord removes his church from the earth.