The US has nothing to gain from the opening up of EU "internal" passenger traffic.
Why would SWA go to the trouble of setting up a parallel EU operation when EZ and Rhino are already entrenched?
Granted, more capacity could lower pricing BUT the trade off would be gridlock, which would benefit no-one (like LGA a couple of years ago, but much worse), and a race to the bottom for the airlines that could offer the cheapest (below profitable) cost.
I can see Leery Micky, Stavros and the big Sir Dick claiming that EU-US open skies would be a win-win.
Kinda like the British auto/motorcycle industry did regarding export, until the Japanese (and others) figured out how to bury it.
History teaches us, be careful what you ask for.
Cheers,dd