Depending on the SDK used during development, some game take a long time to develop, so might get lucky if it was playable on lower firmware, because god of war 2018 was playable on 5.05 PS4.
it may work, but there's no way to know until the game is released. as psn games generally say, "an update may be required to play this software." 4.51 is kinda old, so it may be signed with newer keys. I'm sure sony is aware of this exploit, and it's one of their most successful exclusives, so I kinda doubt it will be using old keys. it's not impossible, just improbable.