Too expensive. How would that be created? Pilots from mainline, but what about the FA's and mechanics? What about the rampers? Would Delta have to purchase new aircraft? What about the sims?

The problem is we already know that regional feed is very cheap, and it's getting cheaper because management continues to lower the payout for each new regional contract. United does it too. Colgan had to give up the Dash-8-400s because United wanted to lower the payments, and Colgan couldn't afford it. COLGAN! So, Republic took them. Same with the Delta regionals. And any management team and board of directors will tell you profits allow the airline to keep flying. It would be just too costly, and very complex.