Delta has no meaningful, sustainable competitive advantage relative to AA (or United) that either or both of those competitors cannot combat and/or replicate. Period.
The constant focus on AA being "#3 out of 3," Delta getting to "at least #2," etc. is a characteristic red herring masquerading as a cogent argument. The reality is that this distinction matters little - what truly matters is capacity, and market access. If AA can get you to pretty much all the same major European markets - national capitals, business centers, leisure destinations, etc. - that Delta and United can, and be within 5-10 bps in terms of overall market share, does the fact that it's technical "#3 out of 3" matter? Of course not. In Asia, the distinction is more meaningful, given that AA currently lacks a major west coast gateway, but there, too, as has already been said, the gap is closing as Delta dismantles its NRT hub and AA ramps up its nonstop Asia service overflying Japan. And as for Latin America, AA's lead is so insurmountable that Delta simply cannot close the gap in the way AA has now done across the Atlantic via the merger. AA is pretty much the size of Delta and United combined in the region, offering a level of nonstop access to every major regional market of consequence that no other U.S. carrier sans a MIA hub can ever replicate.
Still some bitter clingers refusing to accept reality ...
the only ones who don't want to accept reality are people who don't know or who won't accept industry data.
If you looked at that data, you would see that 45% of AA's European capacity is to/from LHR, the highest percentage of European capacity to any one city. Even DL with two large dual partner hubs at AMS and CDG has only 40% of its European capacity at those two hubs.
AA has 15% of its capacity at CDG which is quite impressive in a competitors JV hub but another 15% is in Spain so more than 2/3 of AA's capacity is in just four cities - 3 of which are oneworld hubs.
DL has just about 55% of its capacity in its top 3 markets - AMS, CDG, and LHR but then has the other 50% spread across Europe. UA only has about 15% of its capacity in Germany, its largest hub.
US' network is comparable in diversity to DL and UA's but it is heavily focused on Star hubs- FRA is its top destination. LHR and Spain are in the top markets and that is sustainable but about 25% of US' capacity is to/from Star hubs.
That is not sustainable long-term based on what other carriers have done and the average fares that US and AA receive in other carrier strength markets (Skyteam and Star heavy markets).
Thus, when you say that AA and US can get you to anywhere in Europe, that is true only if a high percentage of those itineraries are via connections which other carriers fly nonstop including from larger markets in the US such as NYC.
as for Asia, all the growth that AA is doing is meaningless in terms of talking about sustainability until it begins to be profitable on at least a seasonal basis. Given that AA is still losing hundreds of millions of dollars flying to Asia and hasn't been profitable for even one quarter in many years, AA can add all the capacity it wants but if those routes are subsidized from something else on AA's network or from lower employee salaries, it is not a sustainable position to be in.
The key principle once again is that AA/US combined have a lot of work to do to rationalize their network, they are still benefitting from US' low labor costs and Star association to make a lot of routes work that probably won't long term, and AA/US' European network is heavily concentrated in a few cities and dependent on an alliance which US doesn't belong to any more while Asia is not profitable.
And all of Asia and Europe is long haul flying while large portions of Latin America can be flown with domestic aircraft.
Add in that low fare carriers will be heavily pushing into Latin America in the next few years on top of whatever a legacy/network carrier does, and pronouncements of how much AA will be growing are premature at best.
I totally get that AA/US is trying to strike while the iron is hot but AA/US haven't come close to merging their operations or networks or dealing with the competitive environment that they will face post merger, including at DAL/DFW and DCA as well as whatever competitive response that will take place if AA starts to add service into markets where other carriers are stronger, including to TLV which was mentioned here as well as continental Europe where DL and UA are much stronger.
no one is saying that AA is dead in the water but too many people here are intoxicated by the promises of rapid growth as a result of a network that hasn't even come close to being rationalized for profitability while failing to appreciate that other competitors do and will protect their core markets, the very ones that AA will try to push into.