Board Thread:General Discussion/@comment-26006155-20190617222636/@comment-26006155-20190623132940

I'm certain that at some point in the future chapters of Deltarune, Kris will visit the real Underground.

Undertale has already loaded a Chekov's Gun, by having the Snowdin wolf who was constantly tossing ice into the river stop doing this for both True Pacifist and No Mercy runs.

That ice was neccessary to cool down the lava around The Core. And without it, The Core will slowly begin to melt and erode over time.

Visiting The Core years after Undertale might well reveal some very, very intersting information about any secret projects Gaster might have been planning before his Beta Timeline death.