Just to clarify, Southwest will be taking over most AirTran flying at MKE by November, but most of the changes have not taken effect yet.
--At this point Southwest has taken over all of MKE-DEN, but most of the AirTran east-west operation is intact.
--By last summer/early fall, the east-west operation at MKE is mixed, with Southwest taking some flights like SEA, LAX and select LGA, but AirTran retaining others like MSP, BOS and DCA.
--By early November, Southwest takes everything at MKE except AirTran retains ATL, DCA and a handful of Florida flights. Recently one of five LGA flights...originally planned to be all-Southwest...has been added back to AirTran.
So most of the transition from FL to WN at Milwaukee hasn't yet happened, but it will within the next 2-5 months. I share your concern that the east-west operation in Milwaukee faces real headwind as Southwest is planning to run it this coming winter -- including bigger planes to fill and much less connectivity. But it's far too early to know how it will pan out since most of it hasn't even kicked in yet.