A potential future in which the cycle stops and no-one can move into the Raw Spirit realm.

So the dead come back to inhabit bodies and the world becomes the Land of the Dead.

Previously this future was tied specifically to the land of The 5 Thunders. With the loss of the celestial egg, spirits were not able to move on in the wheel. Eventually the astral became so full of dead spirits that they began to pass over into the real world where they began to inhabit bodies.