Anyway, we're talking about history here, so in that case you have to look at historical evidence not only in scripture, but also outside of scripture. But, there is scriptural evidence for there being actual churches in Ephesus, Laodicea and Thyatira.
Scriptural references to the church in Ephesus:
Ephesians 1:1 Paul, an apostle of Jesus Christ by the will of God,
to the saints which are at Ephesus, and to the faithful in Christ Jesus:
Acts 20:16 For
Paul had determined to sail by Ephesus, because he would not spend the time in Asia: for he hasted, if it were possible for him, to be at Jerusalem the day of Pentecost. 17
And from Miletus he sent to Ephesus, and called the elders of the church.
Scriptural reference to the church in Laodicea:
Colossians 4:13 For I bear him record, that he hath a great zeal for you, and
them that are in Laodicea, and them in Hierapolis. 14 Luke, the beloved physician, and Demas, greet you. 15 Salute
the brethren which are in Laodicea, and Nymphas, and the church which is in his house.
16 And when this epistle is read among you, cause that it be read also in
the church of the Laodiceans; and that ye likewise read the epistle from Laodicea.
Also, the following doesn't refer to the church in Thyatira per se, but does mention a Christian who lived there along with other Christians in her household.
Acts 16:14 And
a certain woman named Lydia, a seller of purple, of the city of Thyatira, which worshipped God, heard us: whose heart the Lord opened, that she attended unto the things which were spoken of Paul. 15 And
when she was baptized, and her household, she besought us, saying, If ye have judged me to be faithful to the Lord, come into my house, and abide there. And she constrained us.
Here is a site that gives some information on the seven churches and what ended up happening to them:
What Happened to the Seven Churches of Revelation? - IMB