I don't understand where this thread is going at the moment.
You can apply to Commutair, PSA, Gojet and maybe Piedmont and Redwing atm without an FAA ATP.
Breeze, Spirit and Atlas want you to already have an FAA ATP and Spirit says already in USA on an E3.
Don't quote me on the finer details of each airline as things change over time.
My point is don't go to PSA or Piedmont and think you will flow if you stay there long enough. Someone on here keeps saying it's not definitely yes or no but I can tell you with a high degree of confidence that it is very unlikely that an E3 at Piedmont or PSA will flow to AA. What do I base this opinion on? Knowing that AA, United etc have very strong unions and hiring short term visa workers would only be tolerated if it meant saving the airline from bankruptcy etc.
Tossbag is right in one thing, there are opportunities here that just don't exist in Australia.