I have great respect for Fr. Taft, but I think his language goes too far in that interview. It is true that in the first millennium the relationship between the Churches was not top-down. But I think simply saying “sister churches” also doesn’t reflect the reality of the position of Rome in that relationship. If we do use “sister churches” it must reflect that Rome is the elder sister with certain rights that other sisters do not have.

The post-Vatican II goal of the ecumenical movement was full structural unity. Is that a pipe dream with the Orthodox?

No, it’s not a pipe dream, but it depends what you mean. The only possible aim for ecumenism is communion. The old notion that the church begins with God, then the pope, and on down in pyramidal fashion, is gone. What we’re dealing with now is sister churches. That’s what we had before the East/West schism. Does anybody think that Rome had anything to say about who became patriarch of Constantinople? Or who became the metropolitan of Nicomedia? Of course not. These guys were bishops there just like we had bishops here, and when they met they’d say, “You’re a bishop? Hey, I’m a bishop too. How’s it going?” They were all in communion. It’s not like Rome was telling them what to do.

How do we get communion?
First, let’s be clear that this is all we’re ever going to get.

When will we get it?
I don’t know. Certainly not in my lifetime. I would suspect that it’s going to take a few more centuries.
http://www.natcath.com/mainpage/specialdocuments/taft.htm