I don't think they believe Paine Field on its own is going to be able to accommodate the expected air travel growth. Yes, it's serving some commercial air travel now, but the consensus was there needs to be a new airport for all this growth.
Paine field can't support what is needed and can't be expanded. But it will continue to service a small percent of the overall need.
The state has created a new commission to start the new airport site selection process over again, but this time it will just be a recommendation.
The previous project that had been going on for many years was site selection and not just recommendation, but their selection(s) pissed off the people and so the whole thing got just got killed recently.
Paine Field would seem to make the most sense but there really isn't much room to expand it. It can probably help in the short/medium term while a new, from scratch airport is built elsewhere.