When John Paul II died, one of the prospects floated to replace him was Cardinal Jean-Marie Lustiger, who had been Archbishop of Paris from 1981 until his retirement 2 months before the Pope's death.
Lustiger's theology was fairly moderate, and combined conservatism with a willingness to be flexible in the face of new questions (for example, he decried the use of birth control in general, but permitted the use of condoms when engaging in intercourse with someone who was HIV positive). He was quite political for a bishop, but that makes sense considering that he was in one of the largest Catholic cities in the world, in one of the largest Catholic countries in the world.
And, of course, Jean-Marie was born Aaron Lustiger, the son of Polish Jews in Paris, becoming Catholic in March of 1940.
Now, I'll admit that I don't know all that much about the Catholic Church, or the specifics of what Benedict XVI did, or the precise theology or politics of Cardinal Lustiger, but I can only imagine the implications that a Jewish-born Pope could have, both within the Church and in the broader world.