The environment for paying a captain $157 per hour to fly to places ATRs used to go is not very ripe.
I wouldn't be too shocked to see DAL throw a few 100 seaters to mainline, but anything smaller is going to stay with connection. The other thing mainline is looking at is how much cheaper the regionals are than what they were. Regionals have come off their 6 or 8% profit margins, and some are even doing "at risk" flying now. This environment gives mainline a chance to fly connection feed for peanuts. Mainline is cheaper than they used to be, but regionals are super dirt cheap now. Why would mgmt. ignore that factor?
-I would expect that whenever DAL gets a new pilot contract, the captain of the smallest aircraft will top out near $200 per hour. Add enhanced retirement, and all sorts of other goodies, and then the regionals will really be a steal. I just can't see DAL agreeing to fly 100 seaters to DHN and MGM while paying some guy around $200 per hour, when they could contract it out at half the cost (or less) that they used to. Do the math on that.