Midway is probably finished for good. Southwest plans to grow RDU from its current 20 flights to around 80 over the next few years, and American is continuing to expand with RJ's.
Wolfpacker, AA failed at RDU with a different kind of operation than they're building now. The 1986-93 hub was run with MD-80's, planes much too big for the O & D traffic in that market to support. Now, with fleets of RJ's, AA is building a smaller, O & D based operation at RDU (other than the LGW-feeding puprose noted by Viflyer).
Midway was always a niche carrier....cost structure and fares of a Cartel-Six carrier, based at an airport that in the end is still medium-size. Maybe without 9/11 it could have survived with the trimmed-back route network it ran after bankruptcy. But in the current enviornment it's probably finished.
RDU still has a bright future though, if Southwest has that kind of confidence in it, and clearly American sees greater profit potential there too.
Need a new airline paint scheme? Better call Saul! (Bass that is)