I will throw this out there to be considered. Every time I go to a base meeting in Seattle with Flight Ops management and above, the question always comes up: Will the company be opening a narrowbody base in Seattle? The answer has always been yes but the follow on question of when this might happen has always been "some time in the next couple of years" or something like that.
If it does happen, I think it will either be a 737 or A320. My money would be on the 737.
Denny