There is plenty of market for the 717. It may not be here in the states, but a lot of opportunity exists for that aircraft in Asia and Africa. Perhaps when this square dance of consolidation stops and the dust settles there will be several start-ups that would, gladly, fly a next generation aircraft like the '17. The point is, AirTran has the capability to change their fleet plan if they choose to.
AAI has almost always been underestimated. Hell, Boeing even told them that they didn't need the '37 and should not deviate from the continuity of an all '17 fleet. Only after Airbus, damn near, gave them some airframes did Boeing come to the table and deal on Leonard's terms......this from my bud at Boeing CC. The analysts have gotten it wrong before and this is likely the case now. AAI has far too much market influence to just go away or liquidate in a fire sale. Nope, that boil on Delta's a$$ is probably going to stick around and fester.