Paths to unity?

Roman Catholics call it "full communion." Protestants call it "Christian unity." Whatever it is, what does this look like? How will we know when we have achieved a truly one, holy, catholic, and apostolic Church?

I wonder about some of the possibilities that a united Church might look like:

1) A return to Rome.
Catholics: We are right and you (Protestants) are wrong. The brokenness of the Church is solely your fault. Repent and submit to the authority of the Church. Abandon your belief in x, y and z and start believing a, b and c (just like we do.)

2) A change in Rome.
Protestants: We are right and you (Catholics) are wrong. The brokenness of the Church is solely your fault. Repent and recognize that our reformations were necessary. Abandon your belief in x, y and z and start believing a, b and c (just like we do.)

3) Unity in words alone.
Protestants and Catholics (to each other): We will believe what we want to believe and you believe what you want to believe. There is no need for us to agree because I am comfortable where I am. Let's just agree to disagree. If we just say we are united, that is good enough for me.

4) Reconciliation.
Protestants and Catholics (to each other): I am sorry for the brokenness of our relationship, it is not acceptable. You were wrong and I was wrong. The division was really no one's fault. I can recognize you as part of the Body of Christ. Let's sit together and grieve about what we have lost. We need to define what our relationship looks like together. I am willing to work hard at this if you are. It is going to be a long and difficult path, with many small steps. Only with Christ's help can we truly, visibly be one.