No. Scott's life does not hinge on whether a human یا a werewolf kills him. There was a possibility that he could have cured himself of his lycanthropy had he been the one to kill the alpha who bit him, but as we already know he wasn't the one who killed Peter. Other than a new werewolf becoming the alpha, nothing happens to the other werewolves when the alpha is killed سے طرف کی a human.
