In the Kingdom, Age follows Age, until the Son turns said Kingdom over to the Father. Only then does God become All in all, and true eternity ensues. See I Corinthians 15.
Please give a citation that states in the Kingdom, Age follows Age...the rest of that passage does read as the Scripture you cite. Also, "true eternity"? Are you stating that there is some "other type of eternity"?
I'm no so certain you can claim that.
Also, these passages should weigh in for your consideration (esp. if you are a "millennialist")...
I Corinthians 15:25-28:
For
he must reign until he has put all his enemies under his feet. 26 The last enemy to be destroyed is death. 27 For he “has put everything under his feet.” Now when it says that “everything” has been put under him, it is clear that this does not include God himself, who put everything under Christ. 28 When he has done this, then the Son himself will be made subject to him who put everything under him, so that God may be all in all.
Jesus, in other words, is reigning now...from the time of His ascension. ...
Ephesians 2:6-7:
And God raised us up with Christ and
seated us with him in the heavenly realms in Christ Jesus, 7 in order that in the coming ages he might show the incomparable riches of his grace, expressed in his kindness to us in Christ Jesus.
As we do our Kingdom work we are reigning with Christ.
Hence, the 1000 year reign is figurative language for the period of time from the time of Christ's ascension until the unknown date of His return. All Revelation passages can be understood by the context of the rest of the Bible. It is riddle-like in nature. If you are not familiar with this approach and don't trust it, consider that Christ Himself points us to this riddle-like nature when He unravels for us the meaning of the candlesticks and the stars for example...then too this
is a Revelation and revelations need to be made plain.
Here for example is the back up passage for solving the 1000 year reign...
II Peter 3:8-9:
But do not forget this one thing, dear friends: With the Lord
a day is like a thousand years, and a thousand years are like a day. 9 The Lord is not slow in keeping his promise, as some understand slowness. Instead he is patient with you, not wanting anyone to perish, but everyone to come to repentance.
Why does this solve it? I believe it is obvious, but...
Jesus points to the 1000 years wherein He reigns with the saints in Revelation 20. This is the Ephesians passage statement above...Jesus and the saints reign until Christ returns on the Judgement Day which is an unknown time as Peter states...basically he is saying it may be short or long. The 1000 Years is used because the Epistle of II Peter has already taught us that. In many ways the book of Revelation is like a quiz or test on the Scriptures requiring us to solve the riddle by using the Scriptures. Where do we go for spiritual knowledge? We are to go to God's Word and find His good and pleasant and precious counsel. He rewards this route.