Well, perhaps I "mis-spoke" in using that word "permanent;" I don't know that I ever said that it referred necessarily to "eternity." On the other hand, your choice of John 15:27 seems particularly interesting. The text:
KAI hUMEIS DE MARTUREITE, hOTI AP' ARXHS MET' EMOU ESTE.
Of course the versions, such as NRSV, translate this ESTE as a progressive perfect, "You have been with me," but the real sense here is "You continue to be with me." It is AP' ARXHS that adds that qualifier suggesting "you have been with me ever since ..."
But John's usage in this verse is not so easily dispensed with. In the Farewell Discourses there are easy shifts back and forth from such statements as that the believer will _be with_ Jesus and his Father where they are to such statements as that Jesus and the Father will come to the believer and _be with_ him/her wherever he is. Then the entire "High Priestly Prayer" of John 17 appears to be making an affirmation about the permanent mutual indwelling of Jesus, Father and "his own"--17:6 "I have made your name known to those whom you gave me from the world. They were yours and you gave them to me." (NRSV). When did they _become_ Jesus' Father's? There is a specific relationship to this witnessing also--and I might say to a kind of enduring witness of these disciples. So that one may ask, "When did these disciples" come to be "His own?" Is it at some particular point in time that "His own" come to have ZWH AIWNIOS?
It appears to me that Time and Eternity are so curiously interlaced in John's gospel that it is difficult to make unambiguous assertions about the sense of the statements John's Jesus makes about them.