If your wife has established UK residency there will be no need to file a PA form. For the long term traveller that never establishes residency outside of the US because they don't remain in a country long enough, have a permanent address, or don't pay tax in a foreign country then state taxes are probably required and I'm not sure if you even qualify as a "bona fide foreign resident" for 1040 purposes.
I know she doesn't need to file a PA return, but as far as I can tell the only way to avoid the requirement to file a 1040 is to formally renounce citizenship.
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