I could see G4 maybe, they could lure some customers to their PIE & PGD flights, while not competing head to head with the other carriers who serve the nearby larger airports. Has G4 gone into a major hub airport other than DEN?
G4 does have nonstop service out of EWR to AVL, CVG, TYS, and SAV plus seasonal nonstop service out of EWR to VPS.
G4 does serve BWI, which is a major focus city airport for Southwest but is not a hub airport for a legacy airline, and has nonstop service out of BWI to AVL, CVG, and SAV plus seasonal nonstop service out of BWI to VPS, TYS, LEX, and TUL.
G4 does serve CVG, which is a hub for Delta Air Lines, and RDU, which is a focus city for Delta Air Lines, and serves MSY, SFB, PGD, and PIE nonstop from both CVG and RDU. In addition, Allegiant will be starting nonstop service between CVG and RDU on November 16th, and Allegiant also currently serves 16 destinations nonstop from CVG.
G4 does serve LAX, which is a hub for American Airlines, Delta Air Lines, United Airlines, and Virgin America and a focus city for Southwest Airlines and Spirit Airlines, and serves 27 destinations nonstop from LAX with 17 of these destinations being served nonstop seasonally.
G4 does serve OAK, which is on the opposite side of the San Francisco Bay from UA's major hub at SFO, with nonstop service out of OAK to 10 destinations, with 6 of these destinations being served nonstop seasonally.
G4 does serve FNT and TOL, both of which are near the Detroit area but far enough from DTW, which is a major hub for Delta Air Lines.
G4 does serve USA/JQF, which is a secondary airport in the Charlotte metropolitan area and which is near AA's CLT hub.
G4 does serve FLL, which is in the Miami metropolitan area and near AA's MIA hub.