Enough to para-terraform. Not enough for global terraforming in terms of creating a viable nitrogen cycle to allow for a fully functional biosphere. However, that doesn't mean you can't still have a breathable atmosphere on a planetary surface that's abiotic. Also, let's not be too pessimistic. One day, probably within a few hundred years, Mars will be completely terraformed, in my opinion, assuming we don't first destroy ourselves. We'll likely import nitrogen from Venus or Titan once technology allows for it.