I know the verses and I am not running from them at all. In fact, in my unraveling they have gained significance even while that significance has changed.
And for an initial warrant for this little excursion at the edge of our imagination, I would simply point out that Jesus signaled realities greater than himself as well. In John's gospel, Jesus reminds us over and over again that he has been sent to do the will of one who is greater than himself. More, he tells his disciples that it is better for him to leave them so that the Spirit might come. Jesus even expects that greater things will actually be accomplished by his followers.
My hunch is that if we had similar discourses from the Father and Spirit they would sound much the same. "It is better for you that I send you my Son," the Father might say. And we can definitely imagine the Spirit saying, "My job is not to seek my own glory, but to glorify the Father and the Son." Back to this in a moment.
I think I would also say that Jesus thinks the Kingdom of God is greater than himself. Jesus is the Messiah, the One upon whom the Spirit rests, and, therefore, the rightful one to announce the coming of the new age. He is irreplacably the inaugurator of the Kingdom of God. More, he embodies the reign of God, his life a living demonstration of the reign and rule of God so that when we follow Jesus we know we are treading on the path of the Kingdom.
Still, Jesus does not proclaim himself. His proclamation is not of the fact of the incarnation. He doesn't say, "Repent, God has become flesh!" And he is coy about his identity in various ways in the different gospels (John, being the exception here). Jesus comes proclaiming the nearness of the Kingdom of God. And in relation to that Kingdom, his earthly ministry is limited. Jesus does not finally establish the Kingdom of God on earth, and his mission is limited in some way to the lost house of Israel. Something greater is still on its way. Evidently, the final realization of the Kingdom of God among humankind requires more actors than just Jesus.
Now I could spend several paragraphs qualifying these last few, offering all kinds of caveats. I will simply stipulate here to all the verses talking about the full-sufficiency of Jesus. I don't think this mitigates against my larger point. And what is my larger point? I was afraid you might ask me that. Remember, I am unraveling.
But for starters, let's go back to the Gospel of John. The drama of abundant life played out in John is not simply an interaction between "Jesus and me." There is a larger drama on display, a story of Father, Son, and Spirit in which none of the divine persons is sufficient alone. There is always a greater than, a someone else, a something more to come. There is always room, always possibility, always abundance. This openness to the other in God is so important for overcoming views of life that are primarily closed, sorted into categories of us and them around narratives of inevitability. This is one of the gains of a Trinitarian imagination, of learning to think of God as three persons.
This is particularly important in mission theology. Many have laid the imperialistic tendencies of Western mission at the feet of a disproportionately large Christology. The work of Christ is finished. The church is the possessor of this finished work. Mission is taking Christ to the nations. It's a closed story. This is sometimes contrasted with a mission grounded more in pneumatology, that is in a doctrine of the Holy Spirit. The Spirit blows where it wills and always precedes the church in the world. A robust doctrine of the Spirit is also often accompanied by a more vibrant eschatology, the future breaking in fresh ways into the present. This is an open story.
Now, obviously good Christology should yield good pneumatology, eschatology, and vice versa. I am arguing not for one or the other, but an open imagination informed by a dynamic view of the Trinity.