I do love a good marketing campaign, I have to say. I wonder how they're going to logistically get the entire cast in to an advert? Individual character/family trails or a feature length advert with the whole cast in like Hollyoaks sometimes do? Will it be a concept advert or will they just use footage from the show? I like the idea of them doing something very dark and conceptual and imaginative. Hope they get the budget to do it properly.
As for the episode itself featuring the entire cast, that will work well as long as it's an hour long episode, which I'm sure it will be.