There are other ways this can play out.
Typically Delta' planners have backfilled mainline operations with RJ's. To the extent that Comair can depend on CVG's orgin and destination traffic, they will continue & grow operations. Remember that when mainline retreated from DFW, Connection grew there rapidly. CVG, unlike DFW, doesn't have a huge competitor like American and can support higher higher revenue sales.
The branded carriers will likely return to a "at risk" flying model. If Delta mainline retreats from the CVG hub it will have an effect similar to turning back the clock to a model more like Comair's business before the Delta purchase.
I expect a DAL/NWA tie up to put more pressure on Delta to outsource (relieving pressure that they have contracted for too many RJ's already). The two forces might cancel each other out, but neither NWA, or Delta, wants to buy a 100 seat jet until the next generation of these aircraft are built. CRJ700/900's are popular in the interim.
Parking airplanes that you have to make payments on anyway is a very difficult decision. Remember how these airplanes were "self financing?" Well. they have to fly to finance themselves....
I would not consider the regionals truly in trouble until Boeing rolls out a 100 seat jet with the new geared turbofans AND ALPA finds its way on scope. Those events are still at least 5 years down the road.
---- and Delta has been hiring Comair pilots (and ASA pilots, and CAL, Jet Blue, Air Force, Navy, Marine, Army too...when you hire 800 in two years all good applicants are getting consideration)