Delta and UA WILL be fine, but at the cost of running feed at mainline wages. AA will have cheaper regional lift they can capitalize on. I do suspect the shortage to reach a point where AA will bring the feed in house, but not before UA and Delta do. Wild-ass prediction is that Envoy and PDT merge within 5 years and eventually stapled. PSA will remain doing REAL regional flying like CLT to ROA in CRJ700's