I've been turning this over in my head for some time now. There's no marriage in heaven, while priesthood is forever. Why?
Perhaps the purely temporal nature of marriage is a theological clue. I don't have an answer just yet, but I wonder if it has something to do with the husband-headed family as micro-ekklesia.
What the Church needs most of all just now is mystics.
Or at least metaphysicians!
I think you are onto something interesting with your micro-ecclesia idea. The psalm verse "You are a priest forever according to the order of Melchizedek" figures in the rite of ordination, as do St. Paul's reflections on Christ prefigured by Melchizedek.
But what I had in mind when I mentioned eschatological witness of celibacy is that, as some of the Fathers put it, the Resurrection ushered in the End Times, that we are now living in the Eighth "Day" of Creation. (Authentic dipensationalism.) Celibacy says to the world that temporal and material concerns, such as those associated with raising a family, are of secondary importance to the spiritual event which is on the horizon.
That is, we are not to live just for ourselves, nor concern ourselves inordinately with what the world considers valuable, but we are to live in the communion of saints, which is not sundered even by death. Our life here on earth is to be lived in anticipation of our life to come. So, the celibate anticipates with his or her very life the heavenly kingdom in which there will no marrying or giving in marriage.