I’m not sure who I am addressing this to, or how old this is, so I hope this helps. Bear in mind that I am not a biblical scholar, nor did I go to seminary. These are just my observations. From what I’ve seen topics in the bible very often have a multi-layered approach to them. For example, when we look the story of the Exodus we can see all sorts of wonderful pictures of Jesus Christ in it.
With the 7 churches though, it seems like many people only want to take one approach and stick with that. (1) The literal approach, that this is discussing the 7 churches in Asia Minor and their character. This is certainly true, but God put it there to be relevant to us. The characteristics of the 7 churches certainly do apply to Christian congregations all over the world; First Love, Persecution, Joined with the World, congregations in recovery, congregations that are full of the Holy Spirit, congregations that have become lukewarm, etc.
These can also apply to various phases of a believers experiences as he walks with Christ, and experiences that first love, and then that distress when the enemy attacks, or we find that we’ve been too abrasive and made enemies, etc, or that point where we find ourselves seeking accommodation with the world around us, or later when we recommit ourselves to Christ. So here we have 3 applications: the literal 7 churches, 7 distinct types of characteristics of a church congregation, and 7 attitudes or even attitude phases of a Christian’s development. I think it also applies to 7 distinct ages of Christianity, beginning with the early church (Ephesus), the church under Roman persecution (Smyrna), the church joined with the world under Constantine (Pergamos), the church in a kind “Babylonian captivity”, the papal system (Thyatira), the reformation that started a work but didn’t finish it; The first Orthodox split and/or the early reformation (Sardis), and so on.
There are other images that paint broad-strokes of the future from the time they were written, such as the images in Daniel and the Beasts of Revelation, so it makes sense that this application would also apply here. So; (1) original churches (2) congregational attitudes (3) individual attitudes (4) Eras. I think all 4 apply and that this is another multi-layered thing.
Like I said, I’m not a theological scholar, but I hope this helps.