This announcement now is only for the start of some exploratory discussions. The end result is far from certain. As far as KEF is concerned I am afraid that there are a lot of things working against it. The proportion of connecting passengers is high and the local airlines rely on really tight connections which would by disrupted by the additional time needed for pre-clearance. It is also my understanding that the Americans want most of the cost to be borne by the locals, both for the initial modifications as well as the operating costs. There are only so many Icelandic tax payers and they can't be expected to pay for this.