I believe that the chapter break between Isaiah 2 & 3 is entirely appropriate insofar as it separates out different subjects; but somewhat unfortunate as it can make the pivotal role that Isa 2:22 has in dividing the individual but connected visions. Isaiah 2 is about the eschatological future; specifically about 'that day' which will have a time of drastic judgment followed by eternal prosperity. Isaiah 3 however is concerned with the immediate; the pending destruction of Jerusalem and captivity of the Jew under Nebuchadnezzar.
A rapid reading of Isaiah 2&3 may lead one to consider that they are actually discussing a similar subject. They both regard Judah and Jerusalem . They both feature the Lord moving in judgment. And they both appear to be bad news for the Jewish people especially the leadership. However I believe that these two events are very different indeed and the bulk of this essay will be spent highlighting the differences.
I believe the first point to note is that Isaiah 2 speaks of a brief period of judgment followed by an apparently extended period of blessing. Is 2:2 speaks of the Lord's temple enduring, it being upon the most important of the mountains and people streaming to it. In Is 2:3 we see the Jew as an elevated and special people with Jerusalem similarly exalted. Then from Is 2:6 we see the Lord having abandoned His people and judgment following. There is not however any indication of extended judgment. It is certainly forceful, causing people to flee for the crevices; but there is not indication of an occupation. I think the image here is one of purging. It is the proud being removed, the idols being eliminated. Once that is done the blessings can ensue.
The picture in Is 3 is very different. Here we have an extended period of misery. Whilst some of the people being removed are worth removing such as the soothsayers there are also leaders, judges and prophets being taken away. Indeed the text states that every means of support and succor is going to be removed. Men will become bitter and will fight each other and a young generation will arise that despise the old. This is not something that would happen quickly. We are seeing a society that is thrown into severe disarray. The latter part of the chapter then takes pains to show the lowly and humiliating fate of the women that have lost their men leaving the picture of Jerusalem desolate.
The other primary distinction between the two chapters is the primary visible agent in the misery. Whilst we know that it is the Lord's judgment that is at work in both chapters in chapter 2 he is working completely independently of any human agent. It is the Lord alone who is seen as victorious, He will literally rise to terrify the whole earth. The picture is explicitly man against God rather than man against man caused by God. Chapter 3 is very different; here we see God using human agents, disease and famine in order to exact His judgment. Thus by implication some are not being oppressed and people other than God may well be getting the credit.
Having seen that the two passages are very different it is worth seeing how they are connected. Keil and Delitsch point out that both sections are introduced by a formula 'the Lord of hosts' which they state is always used to introduce a section and 'proves' that these are two separate oracles. I certainly do not have enough Hebrew to add any weight to their statements however I do note that at least in the English chapter three appears to be an explanation of something that has gone before. 'For, behold, the Lord, the LORD of hosts,...' One therefore has to wonder what is being explained.
In Is 2:22 we see a bald statement that men should be considered of no account for God is ultimately the one that should be noted. One might almost imagine a stifled snort of derision from anyone looking at the terrible social injustice that was currently happening in Jerusalem. If God is so great and if God works in judgment then what is He doing about the here and now? That I believe is the question which is then answered in the following verse (Is 3:1). He is about to pull the rug out from under their feet. The leadership is going to be gutted and social disarray is going to ensue.
The final point to note is that chapter 3 contains no language which would suggest any for of distant event horizon. In chapter 2 we read about 'that day', and 'planned day' and a 'day of the Lord'. In chapter 3 we read of what he 'doth take away' or is 'about to do'. I therefore believe that these two events are not just different in nature but also very different in timing. Isaiah 2 is a distant look at a time which is still future some twenty seven hundred years after the prophecy was made. Isaiah 3 was fulfilled within a time span which allowed for some that heard the message to experience the effects.
In summary we have looked in some depth at two flowing and graphic accounts in consecutive chapters of Isaiah. However by close study we have seen that the conditions that prevail in the two chapters differ markedly in duration, nature and primary agent. The first uses an eschatological horizon to detail the tribulation followed by the millennial kingdom. The second uses a very near even horizon to detail the coming destruction of Jerusalem by the Babylonians.