After having repeatedly examined my conscience before God, I have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry. I am well aware that this ministry, due to its essential spiritual nature, must be carried out not only with words and deeds, but no less with prayer and suffering. However, in today’s world, subject to so many rapid changes and shaken by questions of deep relevance for the life of faith, in order to govern the bark of Saint Peter and proclaim the Gospel, both strength of mind and body are necessary, strength which in the last few months, has deteriorated in me to the extent that I have had to recognize my incapacity to adequately fulfill the ministry entrusted to me.
For this reason, and well aware of the seriousness of this act, with full freedom I declare that I renounce the ministry of Bishop of Rome, Successor of Saint Peter, entrusted to me by the Cardinals on 19 April 2005, in such a way, that as from 28 February 2013, at 20:00 hours, the See of Rome, the See of Saint Peter, will be vacant and a Conclave to elect the new Supreme Pontiff will have to be convoked by those whose competence it is.
So in March there will be a new pope. It's difficult to think of who would be his likely replacement. Scola is a possibility, but I'm inclined to think that the cardinals will still be reluctant to pick an Italian. Dolan is a possibility, but I think the cardinals will also be reluctant to pick an American. Ouellet, being Canadian, might be possible, but popes tend not to be like their predecessors, and Ouellet is nicknamed the Second Ratzinger. Scherer is another might-be-considered, but he might not be regarded as strong or forceful enough. The two most likely Africans, Turkson and Sarah, are in the same boat. Lots of other candidates are likely too young to be seriously considered: cardinals are generally cautious about anyone who might end up being pope for a long time. Of course, any baptized male in principle can be made pope, but only cardinals have since the fourteenth century.
My bet, if it were admissible to bet on such things, would be on Ouellet, thus giving us the first North American pope, but you can never tell.