Has the papal states ever expanded on your game?

[The New Che Guevara]

As for assasinating the pope, its been a while, but I believe even assasins with max subterfuge have way too low of a chance to make that as a plan really feasible

Says you, with my english campaigns, it was just me, the pope and rebels. I had full control, trying to remove the papacy fully (damn impossible) and I just sent my assassin's after him. I have a 95% chance on it working on the pope at one point.