The messages to the seven churches are not apocalyptic in style like Daniel 7 or Revelation 12. They are “prophetic letters.” They are more like the letters of Paul or Matthew 24 than they are like Daniel 2. So their primary message was for seven actual churches in Asia Minor, the ones that originally received them (Rev 1:4, 11). By extension, as one would for one of Paul’s letters, these messages have value for all those who read them (Rev 1:3; 2:7, 11, 17, 29, etc.).
There is, however, a case to be made to see these seven messages as prophetic of the condition of the church from the time of John to the Second Coming of Jesus. There are several evidences to support this. 1) There were, for example, more than seven churches in Asia Minor at the time John wrote. From the letters of Paul we know that there was a church at Colossae, only a few miles from Laodicea. The letters of Ignatius (a church leader who wrote around 110 AD) go to some of the churches mentioned in Revelation but also to the nearby cities of Magnesia and Tralles. So the choice of seven churches itself seems to have meaning above and beyond the immediate situation.
2) The spiritual conditions in those churches parallel the spiritual conditions of Christianity in different historical periods from the time of John until today. In other words, embedded in these messages to seven historical churches was a grand survey of the major developments of Christian history. The church began strong in the apostolic age (Ephesus), and then went through a period of persecution (Smyrna) followed by compromise and accommodation to the Roman world (Pergamum and Thyatira). The Reformation (latter part of Thyatira) was followed by the spiritually dry period of Protestant orthodoxy (Sardis) and then a second Reformation and worldwide missionary endeavor (Philadelphia). The church today seems relatively indifferent to the claims of Christ in the New Testament (Laodicea). So the broad themes of the seven church messages parallel the broad sweep of Christian history from John’s day to our time.
3) The message to Laodicea parallels John’s appeal to the last generation in Revelation 16:15. The appeal to the world at the time of the battle of Armageddon contains a combination of four major words found elsewhere in the Bible only in Revelation 3:17-18 (seeing, nakedness, shame and garments). So Laodicea is the recipient of God’s last gospel call, placing it in some sense at the end of Christian history in John’s mind.
4) A number of features of the message to Philadelphia seem to imply the nearness of Jesus’ return in way more dramatic that other references in the seven church messages. For example, “I am coming soon” in Revelation 3:11, echoes end-time uses of the same phrase in Revelation 11:14 and 22: 7, 12, 20. So the letter to Philadelphia seems to have special significance as Christians near the end of the era.
All four evidences support and extended meaning for the seven church messages in Revelation 2 and 3, a meaning that goes beyond the original situation and includes implications for the larger trend of Christian history.