Following my whimsical, not to say preposterous “tall tale”, just posted, I thought I should add a little gravity to the situaiton by quoting the words of an English friend who is much more informed about these things than I:

I recall reading (can’t remember where) that Williams had in fact already made up his mind to step down soon – I don’t think it can be directly linked to the Holy Father. One can always hope, I suppose: Fr X – who knows Williams well – told me years ago that Williams had come very close to becoming a Catholic when he spent some time at Parkminster trying out a possible vocation to the Carthusians. He is a knowledgeable admirer of Balthasar, de Lubac, Maritain, John Paul II and Benedict XVI, and his relations with Benedict seem to be genuinely very warm. On sexual matters (including homosexuality) he does seem a wooly liberal, but I believe he has serious reservations concerning same-sex marriage (he may even be against it): I am not a Williams watcher, so to speak, and can’t say for certain. It may be uncharitable to suggest, but I suspect he is resigning because he doesn’t want to preside with authority over the huge same-sex debate that is just beginning to erupt in the C of E. His generation is uncomfortable with authority (the new generation of leftists is not): he will want to participate actively in the debate but not direct it. Still, when the smoke clears from the ruins, I can think of less-likely converts than Rowan Williams.