I dunno about
COS as a hub airport for a full service carrier. There just aren't open gates in the main concourse, and only 6 in the East concourse, which US could take, but what about ticket counters?
There's also almost nothing to do in terms of food or shopping.
I thought about
COS being a great place for US in the past... but with Star Alliance partner
UA at
DEN, and relatively weak O/D from the city to nonleisure destinations, who knows.
WP only served 22 cities from
COS at their height, and while every plane went out almost full, who knows what the yields were.
N