...from what I hear from friends at KXRLG (Kings Cross Railway Lands Group) final council approval for the 'armadillo' redesign haven't yet been given, as a few objections have been raised by some sticklers for tradition. It seems though that the council is likely to approve in the end, but you know how it goes with these planning application things...
Part of the problem is that the 'back' of the building (facing the Scala) is owned by London Transport, as they have doors there that go down into the underground, and this section takes up a fair amount of space in the property. From what I gather the armadillo roof bit will house some of the more functional aspects of the building (ventilation or what not)