something like CLT-DUS/STR/HAM may be more likely to be on a 321XLR. but FRA and MUC will be staying. CLT is unique in how well it's able to serve those two cities for AA
While DUS and HAM could work from CLT with the XLR (I do not mention STR on purpose) I think that it would be smarter to serve those two from ORD or JFK, as the local traffic demand is MUCH higher here. In 2019 CLT had 9,6 passengers a day oneway from DUS and 7,5 from HAM, Chicago had 39,3 from DUS and 44,4 from HAM. (NYC-HAM: 155!).
AA does not do well in Germany, and never has. The problem is point-of-sale from Germany. They've flown ORD-DUS in the past, when Air Berlin was still in business, and even with connectivity on the ORD and DUS end, they could not make it work. HAM has not worked out for UA at EWR (a route it inherited from CO) even with a big hub at EWR and being tightly connected with LH. I just don't see AA adding very much of anything to Germany out of JFK down the road, even with the 321XLR when it arrives on property.
One of AA's first routes to Europe from JFK in 1987 was to FRA (alongside ORY and ZRH and a short lived LYS). The FRA route was pulled in 1990 or 1991. AA also also not been able to make FRA work from MIA (it tried in the 2000s), and the PHL to FRA/MUC routes failed as well. DFW and CLT work because of (1) feed, and (2) cargo.
The 321XLR might allow JFK to FRA/MUC not secondary Germany for the correct reasons you mention, if AA tries secondary Germany it'll be PHL or CLT as it will rely on US based connections.
Also, I don't get the A.net obsession of "it was tried 30 years ago...blah blah blah" as that has zero relavance to aviation today.
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