aside from one person (who knows more than me) proposing it as a finno-ugric language, everything I have read assumed it was P-celtic. I find the question fascinating and would assume the dna studies being made now would propose some ideas, but aside from carved stones and the above material, what else is there to go on?
I would think that either Basque-related or Finno-Ugric would be good candidates. I'm also curious if Minoan falls into one of those groups or was something else, perhaps related to Etruscan.
Y haplotype ping...