Yes, Paul mentions ages in the plural, but neither Paul nor any Scripture writer, speaks of probation during ages to come. It is as grievous an error to be ignorant of what the Apostle says of those ages, as to be as so many are, ignorant of the fact that future ages are mentioned.
Paul says that GodIn the ages to come will show the exceeding riches of his grace and loving kindness toward us in Christ Jesus. During this age God tells us of his love, but he has not yet "shown" or manifested it. He loves all, and will show his love for all, but The Church, head and bodyall in Christare greatly beloved, and in and on and to these he will manifest the exceeding riches of his favor and loving-kindness exalting and honoring this anointed body. It will commence with the Millennial age, and when its work is complete, man and his earth home made perfect and the kingdom delivered up to God (1 Cor. 15:27,28,) then, says the Apostle, there is yet more honor and glory to be revealed upon and through this glorious Christ, each step in God's plan, each age opening up a further development of God's unending programme, and furnishing fresh opportunity for the display of more and more of the exceeding riches of Jehovah's grace and loving-kindness toward us, in Christ Jesus.
If God has appointed times (or years) of restitution and limited their number to one thousand, and declares that then Christ will deliver up the kingdom to the Father (1 Cor. 15:27,28,) who could not accept of anything imperfect, then on the reliable authority of these statements, we may assert most positively that there will be no probation beyond that time.
God's revelation closes with the symbolic presentation of the blessings of that age, and winds up by showing that during it, all who will to have life, shall have it, freely, and those who will not conform to God's law shall be utterly destroyed. And as though to make it doubly clear and to prove to us beyond question the end of evil and its train of pain and misery and death, it is written: There shall be no more death, neither sorrow, nor crying, neither shall there be any more pain: for the former things are passed away. (Rev. 21:4,5.)