Like, lets say she won the war; she transformed all humans into mamono/incubus, and got the strength and power from the Cheif Goddess. But, despite having these new powers she is unable to make mamono give birth to incubus babies to continue the world population, no matter what she does with it.
Eventually she'll realize that the centuries of war was for nothing, and that the mamono will slowly go extinct once the majority of incubus die from old age (Im sure there would be very, VERY small exceptions).
How will this affect the MGE world?