Would echo that I think biz travel is even more concentrated than 80-20...probably more like 95-5. Most people get little to none, and some get probably more than they need.

It used to be the % of Americans with passports was pretty low, but post-9/11 changes made 'em required for places like Cancun/Bahamas or cruises where people might've done without them before.

Also, all the mergers and consolidation that led to recent negative changes in FF programs, among other things, also were bad for flight cutbacks and cities like MEM or CVG really losing flights. And second-tier cities like CAE or GSP would always struggle to get or hold service. My hunch is you have bugger and bigger sections of the national map where people either have to put up with high legacy fares or drive quite a distance to the nearest truly competitive airport.

Allegiant is an interesting bet, as they'll go to some places with minimal service like CHA or FAR and fly either to Florida or Las Vegas, targeting vacationers.