I received news today that Alaska Airlines is not going to renew their bid for serving Adak. The Essential Air Service subsidy from the DOT is due for bids this coming summer and Alaska will not be bidding. They promise to continue service until another company picks up the route, and at that point they will be out of there.
The new EAS subsidy is scheduled for July 1, 2012. It is possible that another carrier will jump on this right away, but it's also possible that Alaska will have to continue serving Adak beyond July 1 if no other carrier steps up to the plate. Right now it's too early to say how it will all shake out.
They were clear that there are no plans to bring Horizon Air to Alaska and that this decision has no bearing on Alaska's EAS agreements in Southeast Alaska.