My belief is that no god can be killed. Their bodies could be destroyed. I believe that their minds will be preserved and they will be able to come back to this world in case they acquire a new body . Guthix being stronger than any god, Guthix could create an avatar or body using natural resources. I think Guthix will return, and claim Gielinor back.
He then restores all in Gielinor, and let it remain in peace. What do you think? Let me explain my theory. I believe godship is just one part of something larger. I believe even though their bodies have died, their minds could still be alive. For example, Guthix has died, but there is equilibrium in Gielinor. Guthix can live so long as Saradomin, Zamorak keep Good and Evil balanced. I believe Guthix can't die if there is the balance.
Guthix as a God of Nature as well, Guthix could kill half. Gods can take over nature and even kill living creatures therefore Guthix might be dead half the time. Guthix could also take out Zaros, which is what everybody knows. But, he's now back.
Guthix has more power than Zaros. I would like to see someone read this and understand what I am talking about. Because I want Guthix to return to Gielinor . If I've understood and believe that this is true, please add my character to your RuneScape friends list.