Though, American will contract even more through the bankruptcy process. It will be hard for them to compete with UA and DL who have much larger scale.
Yet, somehow, a combined US-AA will be better able to do what AA alone cannot do, like stem the loss of revenue in NYC, CHI and LAX (where DL and UA/CO are harming AA in a big way)? US just gave away most of its LGA slot portfolio in exchange for a much smaller number of DCA slots.
What does US have that AA currently lacks? What's left of the NE Shuttle. By definition, that isn't designed to feed international flights.
US has a large presence at DCA. Doesn't do much to help AA counter UA/CO's large international operation at IAD.
US has very little presence at ORD or LAX. US brings no assistance to fighting DL's international domination at JFK. US doesn't strengthen AA's domination at MIA.
US has a large hub at CLT and owns most of the international flights at PHL. Which of those helps capture revenue away from DL? Which of those helps capture revenue away from UA/CO?
Yes, there are smaller airlines that do well like AS but they are much less focused on the hub and spoke model. Large airlines (like DL, UA, and to a lesser extent US) need the feed to fill their international flights (where the real money is).
AA (as it is now), is running five hubs but with half of the passengers of their rivals. UA has seven (and yes, I am not counting CLE and DEN is nothing to write home about) and yet they have twice the market share. It is going to happen IMHO.
LAX really isn't a "hub" for any airline - no airline runs banks of connecting domestic flights - LAX is an O&D airport and a huge international gateway. The big three (UA, DL and AA) all run lots of flights to feed the international schedules and lots of domestic O&D (like the transcons). Same with JFK. It's not a domesti connecting hub for AA or DL. Like LAX, it features lots of O&D and lots of international flights that need feed, but no banks of connecting flights like found in a typical inland hub. MIA? Just like LAX and JFK. Lots of international flights plus flights to feed those. ORD and DFW are true domestic connecting hubs plus plenty of Europe, Asia and S America flights.
Phoenix? O&D plus domestic connections and no US flights to Asia, S America or Europe. CLT? Domestic connections, Europe, very little S America and no Asia. PHL? Some domestic connections, Europe and no S America and no Asia.
I just don't see where the combined US-AA is going to be a more formidable competitor against UA or DL than the current AA. Doesn't mean that Parker won't try to take over AA, just that the resulting combo won't be any better able to compete against UA or DL than AA without the PHX, CLT or PHL hubs or the DCA slots or the NE Shuttle.