1/9/2024 will be the final day of Spirit service at DEN. Current Spirit routes ex-DEN are FLL (also served by UA and WN), LAS (F9, WN, UA), and MIA (AA, UA, and WN). Spirit cites GTF engine availability and low performance of routes from DEN. This will leave Frontier as the resident ULCC in Denver. Frontier is also rumored to be drawing down east-west flying via Denver (see thread in Frontier forum). Perhaps Frontier will look at readding FLL or MIA without Spirit on the routes.

Link: https://kdvr.com/news/local/spirit-airlines-to-end-service-at-denver-international-airport/