Since somebody theorized it on reddit, I'm going to concur with his guess on certain things dealing with the Cloud of Darkness.

There's a possibility that the reason the Cloud of Darkness is one of the (if not the) most powerful voidsent is because she's a shard of Azem. It would be a fitting thing if that was the case, and also show what could very well have been a similar fate for us had we become a Lightwarden. Again, it's a guess, but would make for some interesting complications. Not to mention it'd be possible to have another shard of ourselves while setting things up for indeed the greatest battle that could happen in existence against Zenos (which we know he wants).