Looks like PDX is going to see some changes for AS/QX and UA passengers soon. Long story short: Concourse E is getting expanded, and AS and QX will move there from A, B, and C, while United moves from E to the south side--all sometime in 2017, and construction starts in January. The renderings definitely look shiny and it'll be nice to fly out of a brand-new concourse, but I'm happy I don't fly UA, since I remember what a mess the south side was during the C expansion when I was a kid. (Not that that's the only reason I'm happy I'm not a UA customer.)
I'd guess it's likely that the lone AC gate will move too to stay close to their Star Alliance kin. Concourse A is going to get pretty empty, though; does anyone know if they have remodeling plans for that area queued up next?