It seems like it’d get increasingly impractical as the years go on to hundreds of thousands and millions of years to write them out that way, but then…I guess technically one may already do this with the preceding years, so future’s fair game for it?
BC - Before Christ
AD - After Christ (but in Latin)
ADR - After Christ Returns (but in Martian)
eh… not quite
it actually stands for “Anno Domini”, which is latin, but means “in the year of the lord”