That's the point. Unlike what many people seem to believe, the differences between the churches are not like arguments between brothers that ultimately are related to their behavior and not to a concrete reality. Our differences are more like different scientific researches claiming to have found facts that cannot both be true at the same time. As sad as it may be, either one of us or both are wrong, but that we both are right is impossible. That's why sometimes people want to leave behind the rigours of clear definitions for "fraternity" and all. True, two scientists with different "facts" can be friends, but tells nothing about the reality of what each believe to be true.
All in all, unionist ecumenism is just a symptom of an age where no Christian church has political hegemony or power to persecute the other while at the same time all churches are equally persecuted by a plethora of anti-christian movements and there is a lot of PR to be gained from showing off as eager to "reconcile" as if the differences were just misunderstandings. When one or all of these factors change, I am pretty sure we will go back to the old "I'm right, you're wrong, that justifies erradicating you" habit or at least some form of isolationism.
What I wish is that we could live in the best of two worlds: "I'm right, you're wrong, I hope at some point you repent and God forgives your sins but you have the right to be wrong and to live accordingly, I hope all the best for you, see you later at the cafe after we go to our respective churches". There you have serious faith, realism, real dialogue, respect, tolerance. Just about everything that unionist ecumenism avoids.
In the future when (God willing) reunion occurs between The CC, OO and EO what who would step down as the Patriarch of Alexandria? The Greek or Coptic Pope? Btw the Coptic catholic patriarch certainly would step down.
Secondly would the Pope of Alexandria still lay claim to being patriarch of all Africa? Considering how big Africa is and the fact that practically 95% of the faithful in the united church in Africa would be Latin. I envision at least two patriarchs in Africa. One for north Africa and one for Sub-Saharan africa considering the size of the continent.
Further would you like a unified biblical canon and singular calendar?
Also, would you want the Latin church to change its discipline of mandatory priestly celibacy within the Latin church itself?
When talk of Union comes up on this forum, I always like to pose the question: "And just what would make a union?" "what beliefs or dogmas would have to be compromised", "can you live in a world of parallel theologies and still be considered 'as one' ?". So, although its fun discussing this possibility over coffee , the idea that this will happen any time this side of heaven is pure speculation.