I agree with much of what you wrote ... it is what I have thought about these matters for some time.
"condition existed through the fall of Constantinople in 1453, up to the final collapse of the Ottoman empire."
I generally agree, although I think that the Ottoman Conquest, coupled with the Porte's incessant meddling in the affairs of the Patriarchate, significantly undermined its ability to function as the Primate already several centuries before the collapse of the Ottoman Empire. And the collapse of the Ottoman Empire gave birth to "national" churches, a concept which, while understandable given the historical context of the age, nevertheless greatly disfigures Orthodox ecclesiology, but is today almost taken as a "given" in Orthodoxy.
"It was implicitly acknowledged in the ecumenical Orthodox Church that the principle of concilliarity cannot be a reality without primacy. I feel that today, we're going to have relearn this, due to the present vacuum in leadership in Orthodoxy and what are, IMHO, the wrong conclusions that are being drawn from it."
Yes, we clearly need both, but we appear to be moving in, perhaps, the wrong direction.
"This vacuum exists due to the ailing condition of the Ecumenical patriarchate, a crisis that has been around for the past 80 years, and is not the result of any one factor."
Yes, this is the critical structural problem facing world Orthodoxy at this time. The current system with the Patriarch of Istanbul is dysfunctional, and we have to be brave enough to admit that. Problem is: will the EP ever leave Istanbul? Probably not, because of the Greek sentimentality associated with that City (alas, it is gone, but the memories will never fade). This is a pity, because when you look at the history of the Early Church, it was *pragmatism* that formed the basis of the Patriarchates, not past glories or history. The leading See in Orthodoxy should simply not be located in a 98% Muslim city -- it doesn't make sense, and it is bad for Orthodoxy. But as Fr. Schmemann pointed out in his prescient essay "A Meaningful Storm", the Greek/Hellenic view of the Orthodox Church is such that the Greeks must maintain their primacy in Orthodoxy, regardless of whether or not that makes sense.
"The result of this kind of inattention is that the faithful become confused, local churches become divided into "super-correct" and "modernist" factions and jurisdictions, and this gives the opening to Rome to pursue the "divide and conquer" strategy that so many traditionalist Orthodox fear and lament."
This is absolutely on the mark, in my view. Clearly, Vatican policy has been, in part at least, to play "divide and conquer" by playing various Orthodox Churches against each other -- most notably by trying (and seemingly failing) to isolate the Moscow Patriarchate from much of the rest of Orthodoxy, trying to take advantage of the tensions between the MP and the EP in Eastern Europe and the Baltics. We have to realize that the Vatican is nothing if not very clever politically. By remaining vulnerable in this way or by allowing these vulnerabilities to become manifest by presenting ourselves in a less than fully unified way, we are simply playing into their hands. We need a reformed Primate. Not along the Roman model, for sure, but certainly not the current model, either. And, as you point out, the real problem is that the longer the current model persists, the more it will become engrained into Orthodox psyches everywhere that the current model is simply "Orthodox", which is unfortunate.
"We may be witnessing the passing of the mantle from Constantinople to Moscow, in terms of which will be the Church with Priority in Orthodoxy. But such transitions take more than a generation to become apparent or to get worked out."
I have often thought of this as well. One significant issue here, however, is that the Soviet period of ROC history is pretty bleak, and it will take a generation at least until the ROC is able to raise up Bishops and teachers that can plausibly inspire the remainder of world Orthodoxy to accept that kind of a role for the MP. And, to the extent that the EP is successful in wresting away from the MP all of the MP's jurisdiction outside the national boundaries of the Russian Federation, thereby reducing the MP's jurisdiction to that of any other "national Church", there will be further difficulties in assigning such a role to the MP -- hence the clever strategy of the EP in actively seeking to divest the MP of jurisdiction outside the Russian nation. There's far more going on there than meets the eye, and it is high politics, Orthodox style, if you ask me.