My understanding was that it was originally meant to be ambiguous, that is how it was written, there is no way to tell from the writing whether it was Bane having assumed Zannah's identity, or Zannah herself with a remnant of Bane remaining, or even an equal amalgamation of both, creating a new personality. It is obviously not clear, like Karpyshyn later said. Every reader was meant to have their own idea on which it was, there would be no right or wrong answer. But I read somewhere that Drew Karpyshyn got so many fans asking him who won, that he just got sick of it and wrote that blog post. That is why he sounds a bit annoyed there.