The needs of the various airports are interesting.
IND's need, of course, is a flight to LHR and/or FRA. That's the worst-kept secret in the state's aviation industry. Unless you try to ship yourself via FedEx, you can't go to Europe nonstop from Indy. For domestic service, I could see G4 adding the glaringly absent AZA flight from IND and WN making SAN year-round. Given the intense AS/DL rivalry going on, I could see DL offering a link to SEA to tap into the SkyMiles base and AS retaliating with PDX. And I wouldn't be surprised if NK finally decides to try IND now that the airport's operating costs are competitive with others in the region (for a while, they were among the highest). Dark horse: a flight to Asia on JL to NRT or HU to PEK using Dreamliners, but I don't see either until after LHR or FRA is proven.
For SBN, the big goal has long been to get AA to come back with flights to DFW and CLT - the former could even get some Zimmer Biomet folks to switch from FWA, as they have a huge AUS presence and FWA-DFW-AUS is easier than SBN-ORD-AUS. DEN on UA is also a good bet given F9's track record and the SkyWest MX base. As soon as G4 goes to Mexico, it's a given that we'll see CUN, and I see VPS because many people as far west as Porter County vacation in that area. I could even see F9 coming back, but to cities other than DEN. These flights, plus allowing Uber and Lyft to operate from SBN (the airport only allows local rustbucket taxis that many complain about), will make SBN stronger. Dark horse: B6 to BOS because of the traffic stimulation to that market.
FWA: PHL failed miserably because the only full-fare ticket purchasers were Lincoln Financial and Comcast. However, EWR is doing very well, proving that it wasn't a northeast flight that was the problem, but the hub. EWR could benefit from an afternoon flight for international connections, and I could see AA making another push into the northeast with DCA if they can scrounge up a slot. Much like SBN, UA could also add DEN from FWA, and FWA has a SkyWest MX base as well. The existing G4 service could be bolstered by LAS for sure and potentially SAV. Dark horse: NK because their current CEO knew FWA well when he was at FL. The only thing that stopped FL from launching FWA, days before the announcement, was the WN merger deal and domestic new route freeze.
EVV: This airport was horrendously underserved under the Bob Working days, but has seen major improvements in passenger numbers. The obvious first bets for new routes are some connections of the dots for G4, and I bet PIE and PGD will come first. This will probably coincide with a withdrawal from OWB because now that passengers have a choice to SFB, they are overwhelmingly choosing EVV. A northeast route should also be a priority for EVV, and I could see EWR working like it is for SBN and FWA. But if AA couldn't make PHL work from FWA with the business ties on both ends, they won't make EVV (or SBN) work to PHL. Dark horse: anything that can improve connectivity to Asia given the Toyota presence in the area.
B721/722/731/732/733/735/73G/738/739/742/752/753/762/763, A300/319/320, DC-9/10, MD-82/83/88/90, ERJ-140/145, CRJ-200/700, Q200, SF340, AS350