When FL first announced the takeover, they said they would keep "some aspects of Midwest's Signature Service."That would be the big question. If you're right then I'm not so certain about a switch in that case.
Buried in their plans it was revealed that they plan to convert all Midwest planes to a seating configuration matching that of Air Tran. In later media interviews, it was revealed that the aspects of Signature Service that Air Tran was planning on keeping were the baked onboard cookies. That's all. No good Buy-on-Board meals. No 2x2 seating. Just cookies. Whooptee-freaking-do.