The Pope just said what all other Popes thought after Vatican II. The Catholic Church is the only way to salvation. All other faiths are not true churches, and therefor all of their followers are going to hell.
Another nice touch to this is that he made this statement from his old office at the Office of the Holy Inquisition, now called the Congregation for the Doctrine of the Faith. It is always nice that the the Catholics remember their roots.
His reasoning for this is that the Catholic Church has a direct line of succession to the apostle Paul. Sounds a lot like a McDojo telling other McDojos that their crappy useless fighting system is better than the others because they can trace their lineage back to some unknown dude in India back when T-Rexes ate cave men.
The Catholic Church's hold on being the direct line from Paul is about as true as when I tell people that I can bench press 800 lbs. All they can be sure of is that when Emperor Constantine united all of the fragmented Christian organisations under one church and appointed his buddy Sylvester I as its head. The penalty for practicing a form of Christianity other than the standard Emperor endorsed version was death. Kind of makes it difficult for dissenters doesn't it?