General consensus is that Luffy will break the Red Line at Marijoa and thereby create the All Blue. The premise is that the Red Line is unnatural and possibly a product of the void century.
But is the Red Line really an unnatural part of OP Earth? We know Lunarians used to live on top of the Red Line before Marijoa. Since CDs founded the current Marijoa at or after the void century, that means Red Line existed before the void century and was under Lunarian occupation.
So, may be Red Line is a natural part of OP World and All Blue has nothing to do with it.
But is the Red Line really an unnatural part of OP Earth? We know Lunarians used to live on top of the Red Line before Marijoa. Since CDs founded the current Marijoa at or after the void century, that means Red Line existed before the void century and was under Lunarian occupation.
So, may be Red Line is a natural part of OP World and All Blue has nothing to do with it.