As you've mentioned, in theorycraft world it's great in Wizards / Human fish decks against other aggro decks or against sweepers. However, I'm doubtful that the real threat to fish decks is other fish decks or Pyroclasm.
My bet: this card will see occasional sideboard play in Vintage.
A fish meta sometime in the future isn't inconceivable. The combo decks can't get much better than they presently are (notice that unrestrictions have driven most recent increases in power with the exception of Griselbargain). At the same time, bears have been experiencing a marked power creep. Thorn of Trinibear isn't inconceivable.