It would seem that Min is seeing the aftermath of a full assault on the White Tower, but I guess that the real problem is trying to identify who would be stupid enough to attempt something so suicidal. It does not seem likely that it would be the Whitecloaks, even though they are camped not far from Tar Valon, and the Seanchan are an awfully long way away at the moment. This makes me wonder if it will actually be a force from within the White Tower itself: either the Black Ajah or a coup to wrestle the Amyrlin Seat from Siuan Sanche. This would explain the horrific amount of death and damage caused and I can certainly see an idiot like Elaida justifying such an action.