You don't think the 750,000 in Snohomish County have a choice in which airport they fly from? I have flown from SeaTac, BLI and Vancouver in order to get the best bang for my dollar.  Remember 16 is the maximum number of flights from Paine Field daily, Alaska has taken 9 of those. In 2021 you will be able to ride Light Rail from Northgate to SeaTac, in 2023 from Lynnwood and even later Everett. How much easier can it get?