I'm really glad to hear the Paine Field service won't be limited to Allegiant, who, as their pricing should hint, has an even worse reputation for customer experience than basically every major airline in the US except perhaps Spirit.

While it seemed uncertain for quite a while, after reflecting on my most recent flight into SeaTac on Alaska, it almost seems inevitable. SeaTac is so crowded my plane had to park with several others on empty part of the apron with no gate access, we disembarked literally on construction scaffolding, and walked to the terminal down a temporary hallway made from plywood and tarps - although improved from a previous flight when the sheet metal shed roof was absent, so we walked in the rain.

Even the North Satellite expansion is expected to only reduce the issues, and major proposed capacity increases at SeaTac are probably 20+ years away, funded by landing fee increases. PAE probably looks dirt cheap in comparison.