What I would expect from a *true* union would be:
From the Orthodox:
Apologize for and a more outspoken condemnation of phyletism;
Acknowledgemnt that the multi-culturalism of RC is the traditional way;
Acknowledgment that the role of the primate is more than just honorific;
Abandon the idea of infallibility of Councils; councils can and have stated heresies, they can and have been reproached by other elements of the Church;
Use the expression "through the Son" after "proceeds from the Father" instead of nothing;
Deal with excessive anti-rationalism;
Translate traditional liturgical rites and use them instead of foreign language rites;
(Just changeed) Organize itself in canonical terms around the world: one city - one bishop; Archdioceses, Metropolias, Eparchies and Patriarchates are not the institutional church per se, but the local diocese is. Supra-diocesical institutions such as Archdioceses, Metropolias, Eparchies and Patriarchates have an *assistive* role for communication and organization of the local churches. The concept is that "The National Association of Hospitals" is a necessary important institution, but it is not a hospital. Each hospital has its own head-doctor and administrator who is the bishop. The Patriarch or Metropolitan is a head doctor of his own hospital, and the "President" of the "National Association", not a kind of "top-head-doctor" that can interfere in every hospital. His authority over the other head-doctors is while members of the National Association, not as head-doctors of their own hospitals. Finally, in case of union, the currently Orthodox dioceses and parishes would become Eastern Rite "ambassies" under the local Roman bishops in the West.
From the Roman church:
Apologize for and abandon the concept of infallibility of the Pope; popes can and have stated heresies, they can and have been reproached by other elements of the Church;
Abandon the monarchical model of primacy. Even if it was fit for Modern West (Medieval to Pre-WW I period) it was unfit for the East during the same period. The primate did not act as archpastor if he chose a model that was fit to just half the Church;
Use the expression "through the Son" instead of "and of the Son" after "proceeds from the Father";
Acknowledge that the Immaculate Conception is a theologumen and not a dogma;
Deal with excessive rationalism and emotionalism;
Translate traditional liturgical rites to local languages and use them instead of "modern" rites;
Allow married men to become priests;
Give the Most Pure Blood of Christ in Communion to lay people as well;
Statues are not a problem per se; yet, church imagery is not just decoration, they are tools of healing and should follow some rules. Church art cannot be over expressive, it should not immitate the body realistically, etc. etc. Church statues should be 3D icons. The artistic depictions of the West though can and should be preserved and developed, but as art, not as the tools of the hospital that is the church;
Abandon the excessive formulation of "Co-Mediatrix";
(Just added) Roman dioceses and parishes in the East would become Western Rite "ambassies" under the local bishops.
From both sides:
Reasses their lists of saints and devotions;
Become more active in the world;
Emphasys on ascetic life as the proper Christian life;
Stop condescending with worldly fashionable ideologies;
Stop condescending with criminal and/or immoral clergy;
Nor separation, nor union with the State: symphony when the State is not Anti-Christian, and outright vocal opposition when it is, if not from the people oppressed under such regimes, but from their brothers elsewhere;
Focus on Christ above all and on saints above celebrities;