interesting. 

for me, the mechanics of the plot twist (the protagonist shoots a character to create a news headline in order to communicate a signal) was just that.  the mechanics.  and the effectiveness of the mechanics depends on (1) the time and place of the story and (2) and how the writer sets it up.  the genuine feelings you and i or any other reader feel don't depend on whether or not the mechanics of this twist could happened in our time and place.  with all the splendor of space satellites and predator drones we still gasped when we read the ending.  no?

would we have gasped if this specific plot twist (headline as communication) were missing?  probably not. so how much of the power of a JLB plot can indeed be credited to the uniqueness of an earlier spy time with different, more artisanal spy methods ?  i say not much.  tell the truth.  why were you so moved?  because a headline was needed and this person's name was it?  it's an interesting twist.  but.  it's everything borges does that creates this affecting story, not simply the time-specific details.

but who am i to say that you can't feel nostalgic when you read the story?  that would make me a bitch and, although you may think it, i'm really not. 

the thing about the kind of nostalgia you're talking about, "for a place or time you never experienced firsthand," is that it's all theory.  you really don't know how you'd feel and you can never find out.  and as a response to the remark that "someone needs to create a word that means nostalgia for a place or time you never experienced firsthand," i suggest "fantasy."  and maybe that's the appeal for you.  it's pure imagination.  and isn't fiction always (fine, almost always) better than nonfiction?  at least as catharsis?    

like this person wrote:

Nostalgia is justified when you lived through an era. I'm not surethat we -- who live now and didn't experience de-segregation, the a-bomb, the Cold War firsthand, life before mass-television hysteria, etc. -- can feel quite homesick for the time about which Borges is writing. Really. OR any other time we did not live through.

my complaint (which you don't mention but i'll bring it up anyway) is that while the idea of "forking paths" is interesting & intriguing, it's (1) cheating and (2) it's dangerous.  and even if quantum physics proved that alternate universes were a fact, i'd still frown on the idea.  take a look at the borges tale.  as the protagonist is setting his plan into motion he says, "The future already exists...but I am your friend."  this statement alludes to an earlier discussion between the old man and him when they talk about "an infinite series of times in a growing, dizzying net of convergent and parallel times." the old man explains, "We do not exist in the majority of these times; in some you exist, and not I; in others I, and not you" and then he adds that in some of these times he is dead, a ghost and even the protagonist's enemy.  he seems to be practically telling the protagonist or, at least, handing over a good defense argument, that whatever he does, it's ok.  don't you think that all that discussion about alternate possibilities and being dead or an enemy somewhat made the shooting easier or less absolute in the protagonist's mind?  i do.  well, that's my reading of it. the false luxury alternate universes offer is that nothing really matters because everything is just a version of something else.  that's dangerous.  nothing is absolute?  nothing really matters?  so i could kill you in this lifetime, but that's ok because this lifetime is the version where i'm supposed to make a mistake and kill you?  actually, mistakes don't really happen in alternate universes.  just actions.  just another version.  yahoo! the things i could do with that view of the world. but.  borges, i think, understood better.  that's why he leaves us with the protagonist feeling like shit.  as he should.