EAR (26 Aug 2017)
"SUDDENLY - What will this possibly be? - Reply to Gino - 13 August"

Gino (13 Aug 2017)
What will this possibly be?"
What will this possibly be?
Isaiah 29:5 Moreover the multitude of thy strangers shall be like small dust, and the multitude of the terrible ones shall be as chaff that passeth away: yea, it shall be at an instant suddenly.
Isaiah 30:13 Therefore this iniquity shall be to you as a breach ready to fall, swelling out in a high wall, whose breaking cometh suddenly at an instant.
Hi Gino, John, and Doves,
In reply to your question –
In the context of scripture, the verses you refer to are part of a long narrative (Isaiah 28:1 to 33:24) about the imminent and sudden judgment to be inflicted on the enemies of God—i.e., the strangers/dust/terrible ones; as well as against the people of God—i.e., Israel/Ephraim and Judah, for their iniquities, disobedience, and unfaithfulness toward God; largely caused by their political alliances with neighbouring Egypt (versus relying on God’s protection).
There are six distinct “woes” in this whole passage—28:1; 29:1; 29:15; 30:1; 31:1; and 33:1—aimed at God’s “rebellious children.”
1.         First, regarding Isaiah 29:5, the prophet has described a “local” judgment in Isaiah 29:1–4, which will fall on Jerusalem (Ariel); and it is this judgment that is afterward compared with the fate of the multitude of Israel’s enemies in verses 5–8, which will occur at a time of sudden destruction (re. your reference above). 
In this narrative Isaiah foresaw the multitudes (i.e., small dust) of strangers and terrible ones that would be allowed to come against Jerusalem and her people because of their blindness, idleness, and ignorance (v. 9–13). In the short-term this prophecy referred to the imminent siege of the land, and Jerusalem, by her current enemies (Assyria and Babylon); but it could also—in the long-term—be applied to the succeeding nations (Persia, Greece, Rome/Germany, and Islamic Caliphates) that came against Jerusalem, and the Jews (during the longer period known as the Exile or Diaspora), and the destruction to be wreaked on those nations on the Day of the Lord.
Thus, refer to Nebuchadnezzar’s and Daniel’s vision of the metallic-man statue (see below), which states that eventually the great statue’s composite parts (empires/nations), will all be shattered into chaff by the “stone that was cut out of the mountain without hands” (Dan. 2:34, 44, 45); referring to the inauguration of the kingdom of God on earth (cf. Isaiah 28:16; Matt. 21:42; Acts 4:11; Rom. 9:33; I Pet. 2:6–8). This scenario refers to the various nations that God used to purify and refine His people during the Diaspora; but in the end times those nations will be judged by God, when the world suddenly comes under His management.
Then the iron, the clay, the bronze, the silver, and the gold were crushed together, and became like chaff from the summer threshing floors; the wind carried them away so that no trace of them was found. And the stone that struck the image became a great mountain and filled the whole earth. Daniel 2:35 (cf. v.44–45) NKJV
The elements that formed this great statue were representative of the chaff or man-made empires that would chronologically rule over the Jews and Judea during their exile—viz., Babylon (gold), Media-Persia (silver), Greece (bronze), Rome (iron), Rome divided, and Rome invaded by foreign elements (clay—i.e., Germanic/Barbarian, and Islamist invaders), which became the iron/clay mixture of peoples, cultures, and religions that devolved into the multiple nations (with individual rulers/kings), which exist today across Europe and the Middle East.  It is only when this end stage of multiple interacting kingdoms is reached, that they will all be swept away like chaff, by the coming of the Kingdom of God on earth (cf. Daniel 7:27).
Both Isaiah, and Daniel foresaw that these multiple, man-made nations would eventually disappear from the earth like unwanted and worthless chaff. The cause of this event will be sudden, and it will occur on the Day of the Lord (Joel 2 and 3, Revelation 6:12–17).
2.         Isaiah 30:13 – This verse is part of the same long narrative, and the picturesque metaphor Isaiah uses here is of a great high wall—perhaps a damaged reservoir, or dam—(or a pottery jug, v.14), which, because of an inherent weakness, or pressure behind it, bulges outward, and suddenly breaks.  In this scenario, the iniquities of Israel and Judah have reached breaking point, and the danger to their nation and its relationship with God is imminently obvious. The breach is sudden; and the judgment meted out by their enemies will fall instantly (probably referring to the Babylonian invasion).
From the context of Isaiah’s narrative, it appears that these two separate verses point to two different recipients of sudden judgment: —first, the strangers and terrible ones who are the enemies of God and His people (Is. 29:5); —and second, those rebellious children (30:1) whose iniquities (in relying on Egypt, rather than God), have reached breaking point (Is. 30:13).  These separate judgments may not necessarily occur at the same time, as you seem to imply in your question.
Thus, Isaiah’s narrative alternates between the judgments against the enemies of God’s people, and the judgments against the people of God who have rejected Him, and turned to outsiders for help and protection.  Both of these judgments are off-set by the grace and redemption offered by God to His “rebellious children” if only they will return to Him. In addition, Isaiah has included some lovely promises embedded in this narrative—
Therefore the Lord will wait, that He may be gracious to you; And therefore He will be exalted, that He may have mercy on you. For the LORD is a God of justice; Blessed are all those who wait for Him.
For the people shall dwell in Zion at Jerusalem; You shall weep no more, He will be very gracious to you at the sound of your cry; When He hears it, He will answer you. Isaiah 30:18–19
God bless you in your search for the truth.