feel free to look at the Census data and the size of the cities... but since air travel is well measured and has its own set of data, it makes far more sense to look at actual air passenger data, not just Census or city size data.
based on actual AIR TRAVEL data, the largest airports for intercontinental travel in the US are JFK, MIA, LAX, EWR, ATL, ORD, SFO, IAD, IAH, HNL. JFK boarded nearly 12.2 million intercontinental (non-North America) passengers last year, MIA 8.7, LAX 8.7, LAX 6.4, EWR 4.5, and ATL 4.0 million passengers. IAH had 2.5 million and DFW had just 1.6 million intercontinental passengers, less than half of the size that ATL had. those are the top five but it is interesting to note that ORD is number 6 with 3.6 million intercontinental passengers.
Even if you look at boardings to cities outside of the US rather than N. America, ATL and ORD change places - meaning ORD has more service to N. America as a proportion of total int'l traffic than ATL but still less intercontinental traffic.
Despite your notion of what cities are more global, ATL is the 5th most globally connected city in the US. DFW ranks 12th and PHL below that. DTW and MSP both rank in the top 20.
If you want to drill down to carriers at those cities to see who has the largest int'l operation, it is even more notable that DL's ATL hub is the 2nd largest int'l operation behind AA at MIA in the US followed by UA at EWR, UA at IAH, AA at JFK, and then US at CLT - which will take a major step backward with the cancellation of multiple int'l flights. AA at DFW is #9, DL at DTW is #10.
the notion that the Texas cities are more int'l than DL's hubs or that DL has a smaller int'l operation in the largest cities in the US is simply not born out by fact.
and specific to the question of the Middle East carriers, let us know which hubs they serve - and the evidence is overwhelming that despite the much larger market size than a lot of people here seem to think regarding DL's hubs, DL has less ME competition in its hubs than does nearly every other hub carrier.
and specific to Latin America, there aren't any new carriers starting new service to ATL; there are carriers starting new service to S. Florida, NYC, and Houston.