That can be a discussion that comes up in the game. Many rune masters and sages probably believe the world can't survive without the True Runes, and try to talk you against sending them away.
The way I see it, the natural world just carries on, and there are no more supernatural powers. Natural earthquakes and storms, yes, but no more calamities being caused by people becoming hosts to True Runes. Mankind can either rely on science, or they can turn to religion, believing in gods and spirits who watch over them.