Yeah, not so sure I'd take it to that same illogical conclusion.
AS has added flights from SEA into AA hubs before, and it hasn't poisoned the relationship. This is no different, and certainly not on the same scale as DL setting up a competing hub in AS's hometown hub.
uh... that is PRECISELY the problem.
AS has treated SEA and PDX as THEIR hubs. They have believed they are free to add flights wherever they want, they can codeshare on whatever they want, and they can sell as few or as many seats to codeshare partners as they want - but they aren't willing to submit their desires to the strategic plans of any carrier.
we can track this like everything else but AA will either not expand into LAX-PDX or LAX-SEA, AS will decide after butting heads with DL that what AS will adapt to what other carriers need to do, or the relationship with AA will either move towards a merger or a breakup.
AS does not have any JVs or revenue sharing agreements with any carriers and cannot have them with other US airlines so AA and DL will be forced to do what is in their own financial best interests without respect to the impact on AS.
DL knew full well that DL's own growth on the west coast would force AA to catch up. AA has had a big red circle around some pretty key markets from LAX because of the AS relationship. AA and DL along with AC both increased service to YVR and AS blinked.
DL would likely be quite happy to see AA add flights in LAX-PDX and LAX-SEA because it would further reduce AS' market presence in one of its top markets.
We'll see if AA is serious about its own internal growth or in trying to protect a relationship with AS that, in order to be what AS wants to it to be limits AA's ability to do what it wants.
and it also is worth noting that as AA continues to rationalize its own network - and it will undoubtedly focus on cutting domestic and not just int'l growth, AA will be forced more and more to shift assets where it has the chance to grow - and LAX does prevent an opportunity to do that.
let's also be clear that based on definitions which comnavia has established regarding Tokyo service, AA cannot "dominate" LAX. They might be the largest carrier but they can't dominate the market.