As of the most recent data available from BTS, the market share for Spirit + JetBlue at FLL had already dropped below 50% even before Spirit shut down. The FAA updates the list of covered airports every government fiscal year based on data from the previous calendar year. So Spirit shutting down won't affect the FY27 list, but FLL might not be a covered airport anyway based on the increased share of other carriers in CY25. But in any case it's still a covered airport for FY26 so definitely no changes before September 30.