The judges ruling talks about someone else trying to merge with Spirit...

"Indeed, the Defendant Airlines and others in the
market, in the context of the unique and dynamic market forces
of the airline industry may decide to take another run at a
merger at any time. The Government will no doubt make its
determination –- as it is duty-bound to do -- as to whether such
a proposed merger sufficiently protects competition. Of course,
while the Court always encourages parties to resolve their
differences without judicial intervention, the courthouse doors
remain open should the Defendant Airlines decide to try again"


Doesnt sound promising for the future either.