^^ Well, I guess it's good to remain optimistic, but that just doesn't seem realistic. My guess is that if there are multiple anniversary episodes it'll be with the ones that we already know about. Say a multi-part the spans from the anniversary to the Christmas special. And/or into season 8.
That's *if* they extend the anniversary theme. I'm not saying they will, but if they do, that's the only way I can see it feasibly happening. I certainly don't see them adding additional episodes in between now and season 8.