UAL just started a program with Lufthansa, at their cadet training center in Arizona. If you are a CFI (with other credentials), and you get hired by Lufthansa, you fly as CFI for your 1500 hours/ATP, and then you go directly to the UAL narrow-body fleet, bypassing the regionals.
The majors in the US have enough applicants to last them 3-5 years, then they don't know how they will keep their airframes flying, hence new programs as described above. AA has 3 wholly-owned regionals that have direct flow-thru to AA, after a certain amount of service at one of the 3 wholly-owned regionals (Envoy, PSA and Piedmont).