I believe the text indicates (I'm not sure where, if at all) that such fulfilled countdowns get spun into new Threats and/or Fronts based on the fallout (heh heh) they cause, as the MC determines. Sucks to be the players. Now they have new problems. And sometimes that's going to happen: players either don't catch, or don't prioritize a problem. Sometimes that's alright: it makes the landscape more interesting.
An unaddressed countdown is one way the Hardholder can lose a Hold, for instance. At that point, the Hardholder shifts from keeping the Hold, to retaking or reestablishing the Hold. Or doing something else entirely. But now that enemy-held Hold has its own impact on the surroundings, with numerous conflict possibilities.