I think it's very interesting that Toph here is the character who remembers the sky. Toph is, well, grounded, pardon the pun.

I feel a little odd about the ending here. "They didn't feel any different. They all talked about the sky and how far away it was" is very... Toph. But "only Toph remembered that they all touched it, always" is poetic in a way I don't recall Toph ever being.