Clealry Kratos, Sony and ND could get rid of Nathan at any time replace him with any otehr character (and they did it with Chloe) and no one could get, neitehr Sony, nor ND nor PlayStation nor Uncharted itself. They could even drop Uncharted at some point and they will be fine.
GOW and Kratos, taht's anotehr story. Kratos is so iconic for every Playstation generation that Sony can't get rid of even if any GOW director wants to. He is the one that many identify PlayStation with. In fact ask your father, your uncle even your grandfather and grandmother whether they know Drake they will say nope while they surely know Kratos' person and his name too.
They didn't just reboot him, make im another person to get rid of him so soon.