Well, the concession of a possibility isn't quite the same as a binding doctrine. It's like the Methodist Church quietly saying that there's nothing wrong with the theory of evolution but oh no, we're not going to be definitive about it. So I don't see this happening at all, until definitive proof of extraterrestrial life surfaces and the Church has to really deal with the theological implications.

What's interesting is more the fact that this is coming from someone in the Vatican itself, i.e. considering the source. It's not on the same lines stare decisis, certainly — but people will take more notice. It's like the difference between a Minister of State musing about public policy and some guy in a coffee shop bitching about same.