Yet I Cor. For he must reign until he has put all his enemies under his feet. Fortunately God's Word is self correcting. Paul understood that Christ would reign until He had put all enemies under His feet. An age is a limited period of time.
Many ages are still just several limited periods.
What is beyond the horizon is also beyond your vision. So it is with many applications of time in scripture. However, in the context of God's all encompassing love we should understand that no one is destined for Hell eternally. God's plan is too great for that. He will finish the work that He has begun.