I wouldn't count on that. Nationwide, AM stations that have for years carried their local sports teams are losing their market share to the point of having to not-renew those team deals. WLS is a recent example discussed on this site:
https://www.radiodiscussions.com/showthread.php?707601-WLS-Lose-the-Sox-and-Bulls
Keep in mind, this is W freekin LS!
The decline of AM listening is accelerating. Many sports and NT-oriented AM stations, even in large markets, have been losing a full share or more every year. Sports teams want an up-escalator increase in rights fees every renewal because (rightfully so), they have no stake in whether the station is AM or FM.
Something else to keep in mind; is the Seahawks didn't make it to the playoffs this past year for the first time in a long time. Say what you will about fan loyalty, there will be a rebuilding going on that the Hawks that will take a while. That's just sports. The question will be, is whether the time it takes to rebuild the team will be too late for KIRO.