I believe that God will not "cease to be the Son" in terms of ceasing to be Jesus Christ, but rather that the specific roles and functions associated with the Sonship—particularly those of mediation and redemption—will be completed. In their view, Jesus Christ, who is the manifestation of the one true God, will continue to exist eternally. However, the distinct role of the Son as mediator will be fulfilled, and God will be understood fully and completely as one.
After the final defeat of all enemies, including death, the Son will subject Himself to the Father. Oneness Pentecostals interpret this as the completion of the Son's mediatorial role, leading to God being "all in all."
While passages affirms the eternal nature of Jesus' priesthood, I believe that His intercessory role as mediator will reach its fulfillment once His redemptive work is fully accomplished.
I totally disagree! You can't look at the Father, The Son, the Holy Spirit as playing roles. There's no role playing.
Who they are and what they have done is permanent. There's nothing temporary about it, no role playing.
Some will say, maybe most, that Christ has always been the Son of God. I'll not argue against that!
I believe God has from eternity past seen The Word, who would become Jesus of Nazareth, as the Son who would redeem man from his sins.
So if someone says, hey Charlie, Christ has always been the Son, I say, Amen!