I don't know about all that.
Consider, for perspective. God Of War releases March 2005 / PS2 releases Nov 2006 / God Of War 2 releases March 2007....on PS3 or?
So clearly this isn't really a "for sure" thing. I'd argue one might think the first God Of War sequel would be on PS3 considering how big of a hit the first game was on PS2, but sometimes things don't always pan out that way and Sony is still clearly looking to move massive units. So it wouldn't shock me if God Of War 2 (or what ever they call it) releases on PS4.
Could it be for PS5? Could happen, but until they say so, I don't really think this is a for sure thing. Sony is known for allowing their teams to hang back and release content on past systems while new ones release.