ASH1111111111
True enough, but given the distinctly low number of American FOs in CX (notwithstanding those on a base), if 50% leave over a few years, I can't see anyone upstairs getting especially worried.
More of a threat to EK, in my opinion.
As for SOS intending to leave; that's all well and good, but to where? Australians have nowhere back home to join, Europeans the same, Canadians the same... Not enough Americans to raise an eyebrow, so that leaves the ME.
Many won't leave one overseas job for another, without substantial remuneration increases. The ME doesn't provide that. OK, they'll put you in a flat in a compound, but that won't be much of a draw. The big pay rises are in the form of Chinese contract gigs, which, generally seek out captains.
I'm sure to get back home, some Americans will apply for US positions, but if it's not DL/UAL/AA, you'd be crazy in my opinion. Career progression elsewhere is hugely stunted or the job is rubbish, from what I see.
Good luck to you if you take the plunge, though.