You posted this fantasy yesterday or the day before. Not a chance.
Assuming you work for an airline, you don't seem tuned into to the economics of airlines. Take ORD-DFW, for instance. For a long time, AA has flown 16-18 daily flights, nearly all of which have been MD-80s. Frequency is king. For many years, there was one daily widebody, and it was cancelled three or four years ago. It served as a roving spare to cover widebody departures at DFW and then later on in the day at ORD.
Today, there are scattered domestic widebodies in the AA system, like the JFK-LAX/SFO transcons, a couple of 777s between LAX and MIA and one or two 763s between LAX and DFW. The JFK-LAX/SFO transcons will be replaced later this year as new 3-class A321s are delivered.
Does US currrently fly widebodies between CLT and PHL? Or between PHX and either PHL or CLT? If not, I don't see why this merger would alter that.
In the early 1980s, AA flew its new 762s between LGA and ORD, configured in two-class configuration. Today, fuel is about six times what it cost then, and fares are only slightly higher. Inflation adjusted, fares are substantially cheaper today. Fuel-hog widebodies between domestic hubs? Only if the goal is bankruptcy.