From what I've seen, most people saying "Xander" are more likely to think future!Xander, friend of future!Willow.
While personally, I think it would be fascinating if it were Xander - I don't think it works either thematically or as a plot point, nor in the logical framework of the universe Whedon has set up.
First the time travel aspect: Whedon has shown in Time of Your Life that this is VERY difficult. Willow had to find a temporal portal at exactly the right moment, she accidently not deliberately caused Buffy to go through it. And getting it open again, required revisiting the mysterious Saga the snake goddess. It wasn't like she just waived her arms and it happened.
Two - there's no indication whatsoever that Xander is in the future with Willow. If anything there's every indication that he is not. FutureWillow is clearly desperately lonely, somewhat insane, and alone. She lives alone. No assistant or aid in evidence outside of Harth. And they make a point of telling us she is alone and has been alone for a very long time, centuries. Hence the insanity. FutureXander being a friend of her's - does not make any sense.
Three - Xander unlike Willow, Andrew, Riley, and Giles - has shown no indication whatsoever of being duplicitious or going that route. You have to dig pretty deep to hunt it. He's talking to Buffy. He gets along beautifully with Buffy. There's no rift there. He doesn't appear to blame Buffy for anything - that has been shown on the page clearly.
Willow - Whedon spent a lot of time and effort both in the comics and onscreen showing a potential slide to the dark side. And has thematic reasons for doing so - the potential dangers of magic.
Riley - Whedon spent a lot of time onscreen showing how dedicated he is to the military and how his head has been played with by Walsh and the military. Also Riley's dislike of magic.
Giles - Whedon has spent a lot of time building on the rift between Buffy and Giles. Also Giles is an authority figure or represents one.
Andrew - we've seen very little of. Has dabbled with magic. And has a shady past. I doubt it is Andrew, but he's more likely than Xander. And he hits the whole, I want to be a superhero regardless of the cost to everyone else theme - Whedon is into.
Xander?? Sure it would be cool and ironic. But there's no build-up. And it doesn't fit any of the themes. It works better from a plot and thematic standpoint to keep Xander in the role he is in - ordinary man or everyman - the guy who watches or sees things. We are often in his pov in the series. Also, he's a good guy, who doesn't have to be a superhero. A counter-point to Willow, Angel, Riley, etc.
You have to look at it from three points: 1) is it physically possible, 2) does it make sense from a character perspective and plot perspective - has there been build-up? and 3) does it work within the thematic structure of the narrative? Or does it go against those themes?
Xander would be counter to the themes, because he's in some ways Whedon's stand-in for himself, the guy who is a bit of a feminist, who has no problem with powerful women. And is not magical. Xander is the only character if you think about it - who does not have magic or use it. Twilight does use magic or something to power himself.
Re: part 2- Why it isn't Xander.
While personally, I think it would be fascinating if it were Xander - I don't think it works either thematically or as a plot point, nor in the logical framework of the universe Whedon has set up.
First the time travel aspect: Whedon has shown in Time of Your Life that this is VERY difficult. Willow had to find a temporal portal at exactly the right moment, she accidently not deliberately caused Buffy to go through it. And getting it open again, required revisiting the mysterious Saga the snake goddess. It wasn't like she just waived her arms and it happened.
Two - there's no indication whatsoever that Xander is in the future with Willow. If anything there's every indication that he is not. FutureWillow is clearly desperately lonely, somewhat insane, and alone. She lives alone.
No assistant or aid in evidence outside of Harth. And they make a point of telling us she is alone and has been alone for a very long time, centuries.
Hence the insanity. FutureXander being a friend of her's - does not make any sense.
Three - Xander unlike Willow, Andrew, Riley, and Giles - has shown no indication whatsoever of being duplicitious or going that route. You have to dig pretty deep to hunt it. He's talking to Buffy. He gets along beautifully with Buffy. There's no rift there. He doesn't appear to blame Buffy for anything - that has been shown on the page clearly.
Willow - Whedon spent a lot of time and effort both in the comics and onscreen showing a potential slide to the dark side. And has thematic reasons for doing so - the potential dangers of magic.
Riley - Whedon spent a lot of time onscreen showing how dedicated he is to the military and how his head has been played with by Walsh and the military. Also Riley's dislike of magic.
Giles - Whedon has spent a lot of time building on the rift between Buffy and Giles. Also Giles is an authority figure or represents one.
Andrew - we've seen very little of. Has dabbled with magic. And has a shady past. I doubt it is Andrew, but he's more likely than Xander.
And he hits the whole, I want to be a superhero regardless of the cost to everyone else theme - Whedon is into.
Xander?? Sure it would be cool and ironic. But there's no build-up. And it doesn't fit any of the themes. It works better from a plot and thematic standpoint to keep Xander in the role he is in - ordinary man or everyman - the guy who watches or sees things. We are often in his pov in the series.
Also, he's a good guy, who doesn't have to be a superhero. A counter-point to Willow, Angel, Riley, etc.
You have to look at it from three points: 1) is it physically possible, 2) does it make sense from a character perspective and plot perspective - has there been build-up? and 3) does it work within the thematic structure of the narrative? Or does it go against those themes?
Xander would be counter to the themes, because he's in some ways Whedon's stand-in for himself, the guy who is a bit of a feminist, who has no problem with powerful women. And is not magical. Xander is the only character if you think about it - who does not have magic or use it.
Twilight does use magic or something to power himself.