A/N: As you can see, I don't think I'm going to be updating this any time soon, I just don't care for Undertale as much as I used to and I can't force myself to continue a story I'm not enthusiatic about. If you want to adopt it and continue the story yourself, PM me.
As for everyone else, the story would've continued on with Naruto and Gaara slowly becoming friends on the note that they're both jinchūriki. The other monsters aren't as accepting, especially Undyne and maybe Sans, this leads to a confrontation between Gaara and Undyne which turns into a bona fide fight to the death. Undyne gets seriously injured, dead possibly, and Gaara runs away. Naruto finds Gaara and they reconcile, they decide to find Alphys next and put everyone's suffering to an end. The rest is pretty linear to the game, they fight Asriel, and then there's a chapter devoted to life on the surface.