From an interview:

We are adopting a new kind of philosophy towards raiding which is kind of inspired by the way we did Zul’Aman, which is that we want the raid to be accessible, you know, not just for 10-man groups but also 25. Then kind of have a hard mode built in so that you get rewarded for doing it in a way that’s more difficult. Sort of with Zul’Aman, doing it in a shorter time, rescuing in the prisoners, that sort of thing. So that’s kind of what we have in mind, a hard mode for it.