From Howard's latest update...

October 31, 2014
SEA base closure
We have made the difficult decision to close our Seattle domicile, anticipated in March 2015. Changes in our operations, flight schedule and fleet renewal have required us to force flying into SEA for some time. As we work to put our pilots in the right places, we worked through the NPDM process as outlined in the UPA to consider this change. After very careful analysis, we concluded that it simply does not make economic sense to continue to maintain the SEA flight base.
This closure will be included in Round 5 of our base rebalancing work, which will be a displacement bid. We expect to open that bid next week and will release more details about other rebalancing work prior to the bid opening, but I wanted to make sure you had the latest information as soon as possible.