This week a rather premature report came out regarding the possibility of union between Anglicans and Rome.
My dad (Archbishop of Sydney) had some interesting things to say about it here . I thought he was remarkably conciliatory for the kind of Protestant he is!
What would it take? Well, I think organisational unity is a distraction and at least in human terms unachieveable even if it was desireable. Far better to work at the local level... Bible study anyone? I think a real unity between believers is a possibility.
Part of the problem is the theology of the papacy. Not the papacy itself per se, but the untenable theology of the Petrine office. If the Popes actually exercised a remarkable biblical and spiritual leadership (as, I have to admit JP II did in part) then the authority of the papacy would become an attractive possibility. But I wouldn't want to be under papal authority in the way that it seems to be construed in Catholic formularies since Vatican 1.