This article actually makes a point that is important to the "mainline to PHL discussion." On the LUS side of the house, the distinction between YX flights (most BNA-PHL flights in most schedules) and 190 fights is minimal at best. YX uses mainline gates at CLT, DCA, and PHL, and the experience is consistent with mainline in virtually every respect.
It's different at BNA, by the way, because Envoy handles Eagle flights. That's one of the last vestiges of the hub.
Well, apparently, they are downgrading the E190's to Eagle/Republic-operated E175's after Feb 14, so it will be short-lived anyway. Maybe when they get the MAX 8 in their fleet, AA will free up some 738's to upgauge one of the BNA-ORD/PHL flights to mainline........
I think you are dreaming too much on mainline to ORD. That route seems destined to be E75/CR9 in the long term, maybe 1 or 2 mainline, but I would not count on it. I'd fly 2x2 over 3x3 mainline config any day.
UA already runs a A319 year round on one of the flights (sometimes a 737 on a second), WN runs a 737 to MDW and I have a feeling when NK enters BNA in the not too distance future, they will launch BNA-ORD (not during the initial launch, but sometime later), which would be run with a A319/320. I just don't understand why AA hasn't upgauged one of 9 eagle flights to a mainline, especially since similar airports to BNA have AA mainline to ORD (AUS, MSY, RDU, STL, heck, even IND has seasonal mainline service!). Yet, BNA, despite being a former hub, does not. They felt the need to upgauge one of the BNA-MIA flights to mainline, but not ORD?
Speaking as someone who is originally from the Chicago area, ORD is much more convenient to get to than MDW for most of Chicagoland. I'd rather fly into ORD than MDW any day of the week. Yet for flying into ORD out of BNA, you have to fly either UA or AA. I don't like flying UA because they are horrible, but at least they have a daily mainline option. AA only has regional jet service. I don't like flying on RJs because the planes are smaller and they tend to be more delay-prone.
Anyway, rant over, but I just wish AA would run a 737 on one of the BNA-ORD flights.......