...the pope wrestled with thoughts about the end of his papacy, perhaps even entertaining a momentous possibility: his resignation.
In the last section, dated March 17, 2000, of a testament that was written in 15 bits and pieces over most of his 26-year papacy, John Paul took stock of his life.
"Providence has seen fit for me to live in the difficult century that is departing into the past," he wrote, "and now in the year in which I reach my 80's, one needs to ask oneself if it is not the time to repeat with the biblical Simeon, 'Nunc dimittis.' "
I just don't see any reference to resignation here. In the full context, John Paul II was obviously thinking about his death, not his resignation. Here is the full context:
As the Jubilee Year progressed, day by day the 20th century closes behind us and the 21st century opens. According to the plans of Divine Providence, I was allowed to live in the difficult century that is retreating into the past, and now, in the year in which my life reaches 80 years ("octogesima adveniens''), it is time to ask oneself if it is not the time to repeat with the biblical Simeone 'nunc dimittis' (Ed: Latin for ``Now Master you may let your servant go.'')
On May 13, 1981, the day of the attack on the Pope during the general audience in St. Peter's Square, Divine Providence saved me in a miraculous way from death. The One Who is the Only Lord of life and death Himself prolonged my life, in a certain way He gave it to me again. From that moment it belonged to Him even more. I hope He will help me to recognize up to what point I must continue this service to which I was called on Oct. 16, 1978. I ask him to call me back when He Himself wishes. ``In life and in death we belong to the Lord ... we are the Lord's.'' (cf. Romans 14,8). I also hope that, as long as I am called to fulfill the Petrine service in the Church, the Mercy of God will give me the necessary strength for this service.
John Paul says that he was allowed to reach the beginning of the 21st century, but recognizes that most of his work is behind him. He wonders, in view of that fact, whether the time of his departure is at hand. In the same way Simeon in the Gospel of Luke 2:29, after seeing the infant Christ, recognizes that his service of witness is over, and prays that God will now let him die ("depart") peacefully. JP then goes on to say that his life was spared in the assassination attempt in order that it may belong to God ("the Only Lord of life and death") even more fully. He wonders how long God will ask him to continue serving Him as Pope, but recognizes that God will "call him back" when He wishes, not when John Paul wishes. He hopes that he will be able to do his job as long as he is called to do it — in other words, as long as he lives.
In context, it seems clear to me that this document does not refer to resignation. The language plays on the themes of life and death, of Providence, service, submission to the Divine Will. And what else would a will talk about?