Given how quick the Formor were off the mark, I think they had pre-cogs saying something big was going to happen. By the time the book starts, I think the possible futures had narrowed down to the end of either the Red Court or the White Council. That implies either the bloodline curse was going to do more than just take out a pair of Wizards or that the White Council's attempt to stop the curse could have ended disastrously. Losing the Grey Council and the Fellowship could have been enough to make the end of the war a foregone conclusion. We saw how the end of the RC came about, though the Grey Council's original plan might have been nasty enough to take out enough of the Court to knock the reds down to Black Court levels of power.