Well, who knows what it will be like in the future. Seattle isn’t losing population, some more suburban part of Seattle (e.g. West Seattle) are booming also. It is possible that millenials will stay put and not migrate to the east side.
Seattle has ok schools. I have a toddler, currently living in Bellevue but the thought of him going to school with a bunch of snobs is scary. Maybe move to Mercer island instead :)