Many former Ameriflighters are now working for majors all over the US and some internationally. Stick it out for three years, get into a type-rated turboprop, get a couple thousant hours of real line/weather flying and two-crew experience, and you'll be a prime candidate. It's no guarantee, but if you do your job, prepare yourself for the "major's" interview, and they're hiring, odds are good. Odds are likely to improve because of a worsening ratio between available, qualified pilots and demand for them among Part 121 carriers.