QI just doesn't work many would like it to work. Consider "Quantum Immortality Lite", where you load the gun with a sleeping pill instead of a deadly bullet.

If you undergo the "quantum suicide" experiment but with sleeping pills instead of bullets, you will have just as many "successors" as if you had done nothing at all. All of the versions of you that go to sleep wake up later.

Since they're alive and remember being you, nothing stops them from counting as true successors. This is different from dead people.