The ruins in the last episode of Battlestar Galactica show an image of New York being destroyed. Or at least, it looks a lot like New York, especially in the very end when you see the New York Bridge. This leads me to believe that we see Earth in the future, totally devestated by some kind of nuclear happening.

The ruins in this Battlestar Galactica show that the nuclear incident happened some time ago, but strangely enough there are no survivors....thus far.

What we know for sure for now is that Tigh will find out who the final Cylon will be. And from the looks of it, it will not be a pleasent discovery. Even though when finding the last Cylon the question still remains who the third party is that is responsible for the visions in e.g. Balthars head. Also we should expect some more information about the records of Pithia and how these records with such detail ever ended back into the hands of the Colonials.

Perhaps this all happened before and mankind will go back to Kobol and start all over from the "beginning".

There are at least several way's to end these series, I hope for one though they will encounter more humans that have nothing to do with Colonial tribes. Lets admit it, the notion that we are alone in this Universe is somewhat medieval and although BSG has been a depressive episode to watch it would be nice to end it with hope.