Your predictions, as usual, assume that the New AA will be = to the Old AA.
Just because the old US (post Parker) did not offer PHL-LHR (or other international city pairs) First Class configurations, doesn't mean it's not viable, or that it won't be started. BA has provided 100% O&D First Class PHL-LHR configurations for many years - with the implication that it's successful. US Air, prior to Parker, provided what was rated at the time, one of the top First Class Trans-Atlantic services from PHL. Also, in predicting PHL versus JFK routes and aircraft types to Europe and Asia, Cargo revenue is an important factor, which may favor PHL and larger aircraft types - for logistical and scheduling reasons.
Nobody would be happier than me to see Parker buck the industry-wide trend and embrace the viability of international first class. I enjoy redeeming miles for Z class (AA's fare code for First Class award seats) and it's pretty sweet to buy a discounted I or D fare and upgrade to First with an SWU (AA's top tier systemwide upgrades). So if I'm wrong and you're right - I'll be very happy!
But let's get realistic for a minute. As we both pointed out, it's been a long time since US offered international F. Even AA removed it from all 58 763s a decade ago (used to be 10 F lie-flat seats on every international 763 - Hawaii birds excluded) in favor of two generations now of crappy J, the most recent one being slanted.. Last year, Horton announced that AA's 47 772s would lose their 16 F suites when they join the DL, CO, NW and US crowd of 2-class international long-haul planes. Inexplicably, AA retained F (although only 8 seats) on its planned fleet of just 20 773s. As AA currently flies 15 or 16 daily flights to London, those 20 planes would barely cover those routes. So far, we've seen the 773s on some LHR and GRU flights. Rumour has long been that AA still sells some F to GRU and EZE. So the planned fleet of 20 773s won't cover all the LHR + the GRU plus the EZE flights.
I think we can agree that the trend isn't positive for those who long for 3-class First Class. Yes, BA has flown F to PHL, and most AA metal to LHR currently has F (all but two daily flights are 772s with F, just two are 763s with crappy slanted J). Look at the OW airlines that are reducing F: QF is keeping it on just its A380s, IIRC. JAL didn't install it on its 787s. On CX, it's been reduced to just six seats. LAN ditched F years ago. I think that BA is shrinking F and won't be installing it on all its long-haul planes.
If Parker takes over in a few weeks and announces that the 772s will keep 8 F suites, the 763s will get several F seats (perhaps 6, like at UA), and that the US fleet of A330s will get their F suites re-installed, then I'll be ecstatic. If he announces that AA's 787s will also get 8 F suites, that will be fantastic news.
But the pessimist in me says that he's much more likely to announce that the 773s don't really need F and instead he'll keep it on just the JFK-LAX/SFO transcons. And that's not because I hate Doug Parker or think he's a lying worthless drunkard snake (although I do think those things about him) - the reason I see him eliminating the remaining 160 F suites (from the 20 planned 77Ws) is that he and the other number-crunchers honestly believe that AA won't sell enough of the F seats to pay for themselves. More of the same decision-making that eliminated F from the 58 AA 763s for the past 10 years even though UA kept F on its 763s. And more of the same decision-making that calls for the elimination of F from AA's 47 772s in favor of "up to 45" lie-flat suites (like the current Envoy suites).
Interntional F is an endangered species, and PHL-LHR is a very short flight compared to many of AA's transoceanic flights, like every flight to China or TYO or Deep South America or even LAX-LHR (which has the 77W for now).
And it really does boil down to this: If US needed some First Class suites for PHL/CLT long-haul flights, Parker has the number of the seat manufacturers and could have picked up the phone. That he did not do so tells me what he thinks (and the other number-crunchers thought) about the prospect of selling sufficient amounts of it from PHL or CLT.
I don't have the data, but perhaps it's possible that US has spilling all the potential F buyers in PHL and CLT (and in WAS) to UA and its 3-class international F partners. Remember that since US was never invited to join the UA/LH/AC immunized joint venture across the Atlantic, US didn't get to share in any of those profits. So if all the PHL and CLT and WAS F customers were buying from other Star Alliance members, and if they can be convinced to buy their international F on new AA, then perhaps I'm being too pessimistic and maybe Parker will announce a huge expansion in AA's international F seat inventory. We'll see.