This description kind of makes it sound like a completely different game, no?
Early on, the fandom focused on the meta side of Undertale, thus not many talk about its main story. If Toby were to remake Undertale, I believe that it would turn out a lot like TS!Underswap.
I know that Narra-Chara is not confirmed to be canon and that it is a hot debate in the Undertale fandom, but, honestly? The line “If you laid down her, you might never get up” is quite literally screaming that Chara is the narrator.
Y’know? Rewatching some playthroughs made me get a new perspective about the game; check out this description of the game:
“Undertale is a game where the main character slowly gains the forgotten memories of someone and discovers a forgotten world alongside its forgotten history”