Ah, but will it be true ecumenism, in the mold of Bl. John XXIII?
We address Ourselves now to all of you who are separated from this Apostolic See. May this wonderful Spectacle of unity, by which the Catholic Church is set apart and distinguished, as well as the prayers and entreaties with which she begs God for unity, stir your hearts and awaken you to what is really in your best interest.May We, in fond anticipation, address you as sons and brethren? May We hope with a father's love for your return? (Ad Petri Cathedram §79-80)
Since BXVI desires dialogue, he will never use such words. In point of fact, he avoided them.