Looks as if nothing for CVG, but at least CMH got CUN
CVG-PHX is the largest domestic route between 2 cities served by Southwest Airlines that is not between perimeter restricted airports, that is not to or from a jetBlue focus city, that is not to or from Alaska Airlines's main SEA hub, and that is not served nonstop by any of the big 4 U.S. airlines (American, Delta, United, and Southwest). There are at least 11 businesses based in Greater Phoenix that have a presence in the Greater Cincinnati, including Best Western, Cold Stone Creamery, DriveTime, Kona Grill, Leslie's Swimming Pool Supplies, Mobile Mini, Petsmart, P.F. Chang's, Republic Services, U-Haul, and University of Phoenix, and there is business travel from PHX to CVG with many Greater Phoenix-based businesses that have a presence in the Greater Cincinnati area and with Cincinnati-based Kroger operating Fry's Food Stores and Fry's Marketplace stores in the Greater Phoenix area.
The Cincinnati metropolitan area is also the largest metropolitan area in the U.S. that does not have nonstop service from PHX on any of the big 4 U.S. airlines (American, Delta, United, and Southwest).
There is a real need for either American or Southwest to serve CVG nonstop from PHX since CVG is a key destination for Greater Phoenix-based businesses that have a presence in Greater Cincinnati, since there is limited nonstop service to CVG from the Greater Phoenix area (with Frontier only doing 1 nonstop a day between PHX and CVG and with Allegiant only having nonstop service between AZA and CVG on Mondays and Fridays), since Delta does not have a hub at PHX, and since business travelers based in Greater Phoenix who travel to CVG from PHX would prefer to travel to CVG on American or Southwest if either one of these airlines add nonstop service from PHX and CVG. In addition, there are some business travelers based in Greater Phoenix that prefer to fly Southwest over other airlines as there are 9 cities that see nonstop service out of PHX on Southwest but do not see nonstop service out of PHX on American, including Buffalo, Cleveland, Louisville, Nashville, New Orleans, Oklahoma City, Raleigh/Durham, Tulsa, and Wichita.
If American plans on adding PHX-CVG nonstop service, it could add American Eagle PHX-CVG nonstop service since CVG is only 1563 miles east of PHX and since the PHX-CVG nonstop route is within the range of American Eagle's E-175 regional jets. American Eagle does operate some routes that are almost as long as the PHX-CVG nonstop route on E-175 regional jets, including MIA-MSP (which is 1501 miles), DFW-YUL (which is 1508 miles), and DFW-YYC (which is 1521 miles). If American plans on serving CVG nonstop from PHX, would AA add nonstop mainline flights between PHX and CVG, or would AA add American Eagle nonstop flights between PHX and CVG?
Southwest could add nonstop service from PHX to CVG since there are business travelers in Greater Phoenix who prefer to fly Southwest over other airlines, since CVG is a key destination for some of the business travelers based in Greater Phoenix, and since Southwest would be able to provide connections from CVG to Southern California destinations through PHX if it added PHX-CVG nonstop service.