Wow, concessions won't save Frontier. It isn't a problem of labor wages (which are among the lowest in the industry) but rather a revenue problem.
Frontier is a niche player, much like Jet Blue and Alaska, what those carriers have that Frontier sorely lacks are code shares and other agreements with other players. Frontier is going to continue to be muscled out of the market by more powerful legacies and Southwest. They need a partner because they will not make it on their own with the current business plan they have.
Maybe if they adopted an ULCC model like Spirit or Allegiant they could carve out their own niche but right now they are trying to be a premium LCC (like Jet Blue or Birgin America) and straddle the gap between WN and UA and it isn't working given their small size.
They either need partners (Jet Blue and Alaska) or to be ridiculously well financed (Virgin America).
FAPA - Concessions will not save your airline, don't even bother.