You keep talking about WN like they are some kind of chump. Remember, they are the ones that pushed many legacies out. Has there ever been a strong WN focus city where they were dominant (like at least 40% of traffic) and got pushed to a second place?
There hasn't been a WN focus city (or former WN focus city) where WN was dominant and where WN got pushed to second place. However, WN did significantly downsize PHL from 70 daily departures at its peak to only 24 daily departures today, but WN was never the dominant carrier at PHL.
While SLC used to be the home base for KN prior to the WN-KN merger and while WN used to serve some additional destinations in the Western U.S. nonstop from SLC in the past, WN did drop some its nonstop routes out of SLC. WN used to serve ABQ, MCI, STL, SEA, and PDX nonstop from SLC in the past, but WN no longer serves ABQ, MCI, STL, SEA, and PDX nonstop from SLC. WN also added SLC-DAL nonstop service and brought back SLC-BUR, SLC-SMF, SLC-SAN, and SLC-SJC nonstop service following the WN downsizing at SLC that took place 5-10 years ago.
WN did significantly downsize at PHL since the last economic downturn in 2008. However, WN did add PHL-DAL nonstop service after the downsizing of its PHL station, and WN will also be bringing back PHL-HOU nonstop service this November.
WN was much bigger at ABQ 10 years ago than it is today, but WN did significantly downsize at ABQ with WN establishing a focus city at DEN, with WN significantly expanding at DEN, with the repeal of the Wright Amendment, and with WN expanding at DAL following the repeal of the Wright Amendment. WN also dropped nonstop service to AMA, ELP, LBB, MAF, SLC, STL, SEA, TPA, and TUS out of ABQ. However, WN still maintains over 50% market share at ABQ, even after significant downsizing at ABQ.
WN used to serve more destinations in the Western U.S. nonstop from SEA 15 years ago, but WN did drop some of its nonstop routes out of SEA. AS also was a much smaller airline 15 years ago, and DL didn't have a hub at SEA until 4 years ago.