Alternate History, Imagined Futures discussion

Bit confused: do you mean there's no reference to a changed timeline in your story, or that events happen in your story that eventually change the timeline?

Hmm, if nothing in the story itself says things are different, I'm not sure that it could even be labeled a subset of alternate history. I get what you mean about backstory, but unless that's clear in the text itself it doesn't really matter for the reader.

But is that clear in the story, or does it assume information the reader is not given? I'm still a bit unsure: I don't know that I can really attempt an answer unless I read the story for myself.

It doesn't really sound like alternate history then. If the point of departure doesn't change things, I don't think it can classified as such. Science fiction definitely sounds like the better designation (I got a Star Gate vibe based on your description).