St. Malachy.

http://www.crystalinks.com/papalprophecies.html

Supposedly he has predicited in very Nostradomian ways a number of popes in a row.

Pope JP2 was the third from the last...
(/e prays for young Pope)

The late JP2, reguardless of how beloved he was, was a little out of touch with current times. If the Church doesn't adapt in some form to current times and find its place in it, the authority of the Pope might be undermined a bit due to being totally out of touch with his flock. There might always be a Pope, but it could become similiar to the British Monarchy in that its more for the sake of tradition than an actual seat of power. It doesn't seem like Dooms day. More like common sense that if you don't adapt you become obsolete.