One final postscript to my previous two posts. The ending of John's Gospel suggests that there were rumours going around in his old age, that he was anxious to dispel; and that the little addendum written at the end of the Gospel by his Ephesian followers (perhaps the whole of chapter 21, as the Gospel would otherwise finish neatly at the end of chapter 20?) at his bidding was partly for this purpose, viz. to dampen people's expectations. One is tempted to surmise that his High Priestly garb added to the mystique of his persona, and helped to feed the gossip.
The interesting thing is that John does not directly say that people are wrong, but merely that this is an interpretation of what Jesus said, and not a verbatim report: he did not say "John will not die", but "If I will that he tarry", etc. There is a degree of ambiguity here, and presumably the addition to the Gospel ("we know that his testimony is true") indicates that John is still alive at this point, although the "is true" might conceivably have been written after his death.
It seems, however - from the ending of the Acts of John - that this rumour persisted nonetheless. And the fact that the final section of the Acts was a liturgical text for his feast within, at most, two generations after his death in the churches of Asia over which he exercised his Apostolic authority, is also interesting. Polycrates does not mention (or rather Eusebius does not say that he mentions) anything more about John's tomb than that it was at Ephesus, which makes one wonder if the assumption story was (as we say) a pious gloss. The tradition that seems to have got about the most is that of the manna, which shakes and moves over his tomb as if he is breathing - and indeed one of the assumption stories seems to play into this tradition, by mentioning that his body was replaced by a "fountain" of earth, which accounts for the stirring of the manna.
Finally then: is the reason for the disappearance of the High Priestly garb and office in Christianity, after the terms of office of both James the Just and John, because John was buried with this clothing? And is a further reason that there was (at the time) a doubt in people's minds as to whether or not he was actually dead, asleep, or even translated, fueled by the ambiguity of the late addition to his Gospel?