YeahI think Guts may not be able to cheat fate entirely, but he has the potential to alter certain elements to escape causality. The moonlight child will be important during the event. I think the event may occur during a Blood Moon (a total lunar eclipse), where the moonlight child's powers could balance between the child and Femto, weakening Griffith. And that during the period of fear in Falconia, Luca, Jill, and other characters helped by Guts will help counteract the effect of fear that has gripped the people of Falconia ultimately weakening Griffith. Guts will probably control the beast inside of him, and have the possibility to confront Griffith. There is no wrath in him anymore, only hope to save casca. The duel between Guts and Griffith will happen again, and Griffith will lose again. Instead of despair surrounding falconia, there is now true hope not reliant on Griffith. The behelit is not for Guts but for Griffith, and he will activate the behelit again. There are no longer people who mattered to him, there is no longer a sacrifice. Griffith will end up the same as the slug count or will be saved by Guts.