Although it's not reasonable to rule out the possibility that the seven churches of Revelation might be refering to certain Church periods that were to follow, I found that I couldn't be as certain on this point as I once was, and now I am more inclined to doubt this interpretation.
Having studied some of Church history, I didn't find that the history of the Church lent itself to the revelation divisions. while a lot of things have happend in the history of the Church, I did not find that any of it resembles the systematic layout given in Revelation.
Having said that though, I will say that one thing that really stands out is that Jesus kept saying, 'Let the person who has ears to hear, hear what the Spirit says to the churches.' Now, the other time Jesus used the expression 'ears to hear' was in Mark 4:9; 4:23; (cf Luke 8:8; 14:35); all of which indicated that Jesus was saying something that meant more than what it appeared on the surface.
From that I surmise that Jesus, in addressing the seven churches, was saying more than it appeared on the surface, but I don't see that he was meaning seven periods of characteristcs of the global Church. Rather, I suspect we haven't yet worked out what he meant and it continues to be a mystery.