The term would actually be "retro-future". What the past thought the future would be like.
Space 1889 would be vintage.
uh, no. space travel in 1999 seems pretty vintage as it actually happened back then.
1889 would be retro-future as it didn't happen.
And in any case, it was a play on Danny's post about being so 1999 and merging the idea of Space 1889 with his quote.
Sorry you didn't get the joke. Danny did.