Somewhat irrelevant, but you've got the wrong USAir livery there. This is the USAIr livery a partial version of which those Piedmont aircraft were delivered in:
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Photo © Frank C. Duarte Jr.
Note the shaded cheatline that is the same in the Piedmont/USAir hybrid livery:
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Photo © Frank C. Duarte Jr.
This similar livery with a blue cheatline would also qualify as a Piedmont/USAir hybrid:
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Photo © Frank C. Duarte Jr.
That became the new interim Piedmont livery after the merger agreement, replacing this:
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Photo © Frank C. Duarte Jr.
But none of the hybrids were ever fully repainted in the USAir livery of which they wore a version; instead they got the titles from the new USAir livery:
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Photo © Frank C. Duarte Jr.
As did aircraft in the blue-cheatline version:
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Photo © Frank C. Duarte Jr.
And ones in full pre-merger Piedmont livery:
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Photo © Frank C. Duarte Jr.
And this is the livery USAir introduced in 1989 when the merger was completed:
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Photo © Frank C. Duarte Jr.
Of course now we have a kind of reverse hybrid with this

:
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Photo © Lyndon Thorley
Oh, and let's not forget
AA has its own precedent with the sort of arrangement you're proposing here:
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Photo © Mark Abbott
That said, I'm not sure we'll be seeing aircraft in
AA livery with US titles, or even (although it is not what you are proposing) US livery with
AA titles. The
DL/NW merger involved no hybrid liveries at all, and
AA could decide to make the same decision. (
UA/CO of course made the unconventional choice of just painting
everything in a hybrid livery, but I seriously doubt we'll be seeing
AA doing that.) I wouldn't be surprised if US aircraft just got repainted into/delivered in full
AA livery with tiny "operated by US Airways" titles, as
DL did with
NW aircraft, while those that aren't repainted remain in full US colors until they're repainted or retired, eventually with "operated by American Airlines" titles after the airlines move to a single operating certificate, again like
DL/NW. Though I certainly hope we see a USAir and/or US Airways heritage livery to go with the Allegheny, America West, Piedmont, and
PSA ones (which hopefully will be sticking around)... Maybe even an
AA 1968 livery "heritage" livery, which could be accomplished by simply failing to repaint a 737.
