The people holding Spirits debts are at a crossroads after two bankruptcies. They continue to pump good money into the business to keep it afloat with the hope of finding recovery on that investment at the end of the day. Any merger or acquisition at this point would require agreement from a majority of the debt holders that they would get some percentage of the value they are owed. The value would have to be higher than selling off whatever is left as assets such as gates, offices, etc. At this point, no one is taking all of Spirit's debts except the current lien holders who are on the hook already. The latest $50 million extension was mostly funded by selling 2 gates at Ohare to American, so really no harm to have one last gasp to see if there is any interest. I think Spirit closes down just due to the burn rate of cash and the time any merger or acquisition would take.

If someone just gave you Spirit Airlines today with no debt, you would need $3+ million a day or $100 million a month just to keep the doors open. These numbers are not just cost, but include all the revenue being brought in by the company. You are basically signing up for a billion dollar a year boat anchor with no debt.