Either it ends like it did in GoW I (where he rules over all the wars of the world, forever doomed to what he became, a being completely devoted to the art of hatred, violence, and loss: War).
He finally lets go of his hatred, hatred against the gods, hatred against fate, and hatred against himself, and the weapons chained to him slip off, the ashes and memories peel off his body, and he finally rests in peace with his family.
I think that him absolving himself of guilt is actually kind of irresponsible. He SHOULD feel guilty for what he's done. But, Western cultures do value the concept of salvation and atonement. And it does seem harsh to make someone suffer forever.
Although it doesn't really sit well for Kratos to "let go" of his sins, but if he doesn't then he's eternally doomed to continue fighting.
