Nobody knows. Several times in the past it has been predicted, but it hasn't happened yet.
We would have all died
You can not breed it anymore unless you already have two Apocolypse dragons. If you have two, then breed them together.
There is no telling how many people will be alive after thee apocalyose. Just due to the simple fact that people belive that when thee apocalyspe will come soon(December 2012). If you belive that is this apocalypse is coming, and will kill many people then if you live after this so apocalypse you should think about doing a sences. Thats just me opinion.