The two lines I mention in the change description – "all thy sons command" and "God keep our land" – could change easily. But I wonder: should a country keep the same anthem indefinitely, or is there a point where you adopt a new one?
There's a lot going for the current anthem just because it's the current anthem. Nearly all of us know it by heart and a lot of us have some emotional connection to some passage, or to the whole song. "The true North, strong and free" still resonates with me.