I wonder what happens if the part where the HKs / Gorosei receive the marking was removed.
Since Shanks presumably lost the mark of the abyss after the seaking tore his arm apart, is it safe to assume that if someone targeted the place where they received their mark, and thus removing it, it could lead to them losing their immortality ?
Maybe it could be Oda's way to find an alternative in their defeats outside of delivering adcoc to everyone