With AS running an E175 I think there's a decent chance MKE-SEA can support both carriers year round. Alaska can serve some connecting traffic at SEA, plus they have a strong following in that corner of the world -- I know people who fly SEA-ORD on AS when traveling to Wisconsin to stay with AS who can now use MKE.
If Milwaukee patronizes SEA reasonably well I have hopes MKE-PDX could be in the future. The E175 makes it possible. Milwaukee loses traffic to ORD when no nonstops exist, and conversely pulls from northern Chicagoland when there are nonstops, so I think it's a real possibility...if MKE supports Alaska.