While the potential exists, have the leaders of the Autonomous churches (EC's) shown any tendency to do such a public rank-breaking in the past?
Oh yes.
Here we have an instance of the Catholic Melkite Patriarch claiming equality with the Pope, both for himself and for other Catholic Patriarchs. This is from the Vatican website
http://www.vatican.va/news_services/press/sinodo/documents/bollettino_20_x-ordinaria-2001/02_inglese/b10_02.html(close to the bottom of the webpage)
H.B. Grégoire III LAHAM, B.S., Patriarch of Antioch for the Greek-Melchites, Syria
It is incorrect to include the Patriarchal Synod under the title of Episcopal Conferences. It is a completely distinct organism. The Patriarchal Synod is the supreme instance of the Eastern Church. It can legislate, elect bishops and Patriarchs, cut off those who differ.
In No. 75, a "particular honor" given to Patriarchs is mentioned. I would like to mention that this diminishes the traditional role of the Patriarch, as well as speaking about the honor and privileges of the Patriarchs in ecclesiastical documents.
It is not a question of honor, of privileges, of concessions. The patriarchal institution is a specific entity unique in Eastern ecclesiology.
With all respect due to the Petrine ministry, the Patriarchal ministry is equal to it, "servatis servandis", in Eastern ecclesiology.
Until this is taken into consideration by the Roman ecclesiology, no progress will be made in ecumenical dialogue.
Furthermore, the Patriarchal ministry is not a Roman creation, it is not the fruit of privileges, conceded or granted by Rome.
Such a concept can but ruin any possible understanding with Orthodoxy.
We claim this also for our Patriarchal Melkite Church and for all our Eastern Catholic Churches.
We have waited too long to apply the decrees of Vatican Council II and the Encyclicals and letters by the Popes, and notably by Pope John Paul II.
Because of this the good will of the Church of Rome loses credibility regarding ecumenical dialogue.
We can see the opposite occurring: the CCEO has ratified uses absolutely contrary to Eastern tradition and ecclesiology!
[00119-02.03] [in096] [Original text: French]