Either this is still all in the mirror

I think it's more plausible that the mirror acts like it does in canon; that is, you see the room you're in, plus some features that you deeply desire; you don't see yourself leave the room unless you actually leave the room.

Harry needs to buy lottery tickets right away.

I see three broad paths the next chapter could take:

1. Hermione, wake up! We won and now we have to rescue Dumbledore!
2. "You thought that would stop me? Now we fight!"
3. "You thought that would stop me? I had just made a horcrux for her, and your Patronus plus my horcrux is how we're going to solve the death problem. You've failed my loyalty test. And after all I did for you!"

(As always, there is the category of "everything else.")