US and others are cutting capacity out of LAS (but it may still have excess- things are REALLY down in Vegas right now, plus you're competing against WN in what is as close to a fortress as they have); I would imagine the same is true for UA/AA out of ORD (and with the new runway, that would make it easy to move in).

FWIW, I've always seen UA and AA as VX's main targets- though they've picked up some nice business out of SEA against AS, I see their next set of expansion targets as being UA/AA hubs: ORD, MIA, DEN, DFW, as opposed to AS markets (PDX is a bit small, though a close hop for SFO and LAX, and operations in Alaska are complicated- plus I'm not sure SEA-IAD/JFK/ORD/LAS is where they should be going, though I'd LOVE it if VX flew LAS-SEA).

I also think they will do some East Coast service (JFK/IAD-MIA) at some point to complement the SEA-SFO/LAX-SAN/LAS they have going on the West Coast as well. Who knows, maybe they could make JFK-IAD work?