Seeing as B.C. stands for BEFORE CHRIST

Do atheists still refer to the years correctly?

Seems interesting that the entire world follows the same calendar...meaning Before Christ is just...what it is.

I wonder how that stuck so well?

You seriously need to learn what "BCE" stands for.

BCE - Before Common Era, Before Christian Era, Before Current Era
CE - Common Era, Christian Era, Current Era

http://en.wikipedia.org/wiki/BCE

But what would they refer to after the Earth is destroyed?