Why would PHL need flights to south america and Asia when JFK can serve that just as well? seems redundant to me to have flights to Asia and South America from both, whether that be from PHL or JFK.OR Ord. CLT-GIG might be not be necessary but i think at least CLT-GRU will stay. While some of the traffic can be routed through MIA some mco will still go through CLT, and there are many destinations that will see service to CLT but not MIA and double connecting to DFW or Mia would be unreasonable.
I'll start this far too lengthy post with "I may be completely wrong."
I'm starting from the premise that not every hub can profitably support nonstop flights to all of the following: TYO, PVG, PEK, ICN, GRU, GIG, SCL and EZE. I think that's a pretty safe assumption. Pre-merger, US flies exactly one daily flight to one of those destinations: CLT-GIG and CLT-GRU is scheduled to begin later this year. From JFK, MIA, ORD, DFW and LAX, AA currently flies 28 peak daily flights to those destinations (not counting DFW-ICN beginning in May). Even with 28 daily flights to the cities on that list, not every AA gateway has flights to every one on that list. So additional long-haul flights to Asia and S America will, of course, be added where the O&D plus reasonable connections combine for the greatest potential profit. Daily O&D between CLT and Brazil is very low, and if most on the CLT flight from GIG are heading back south 500 miles to MCO, it doesn't make any sense for the S American flights to overfly MIA on their way to CLT. The extra miles aren't just inefficient from the airline's perspective (fuel, labor, etc), it needlessly adds almost four hours to the journey for the mouse-bound.
Sure, CLT has some very small spokes that get 3-4 daily Dash8 flights. Those customers already double connect to get to most long-haul destinations on that list above, and unless UA or DL swoop in with convenient connections to ATL or EWR or IAD or IAH, those people will still have to double connect. The fact is, those tiny spokes that are connected solely to CLT (and not to PHL) don't generate very many trips to S America or Asia.
Why would PHL have flights to S America and Asia and not CLT? Size. O&D. When US applied for China rights a few years back, Parker selected PHL as the gateway. The PHL metro area is triple the CLT metro area population, and despite not having as much domestic O&D as its population would indicate (in part due to Amtrak's convenience to NYC and WAS) PHL has more international O&D than CLT.
During the past few years, we've repeatedly heard that AA needed a southeast connecting hub, as the hypothetical RIC-JAX passenger did not have a sensible AA connection. But AA didn't need CLT as a gateway to Asia or S America. Both RIC and JAX are connected by AA to MIA (taking care of their S American needs) and both are connected by US to PHL, enabling connections to Asia. Congestion at JFK might prevent AA from connecting all the Richmonds and Jacksonvilles to JFK - but no need to, since US already connects them to PHL. And sure, some of the residents of the one-horse towns that have flights only to CLT might still need to double connect - such is life in very small town America. Most international passengers are in the big cities, not those one-horse Dash8-only towns. If O&D from PHL is greater than from CLT, then that's where I predict new AA will start new long-haul flights.
Merger or not, IMO, AA needs to start flights to China from JFK - one of the biggest USA O&D markets to/from China. Many multiples of the daily China O&D from PHL or CLT. Assuming that US has been sending a lot of its loyal customers to help feed UA flights to Asia from EWR, ORD and IAD, there should be some ready-made customers to support some new flights to Asia from ORD, PHL or JFK.
Like I said, I may be completely wrong.