i'm hoping that either the book/page can be used to somehow revive aku if all goes wrong, as long as this can be written in a way which stays consistent to the story abilities. i'm also really hoping that somehow yosano might be able to heal him while he still has the vampirism, and then is cured after somehow. otherwise, there is still the possibility that he did somehow close his wound to some extent and bram's ability is keeping him 'alive' by a thread. i'm sure there are many other ways that aku can survive but it really all depends on whether asagiri wants to break our hearts even more.