Community Manager Bashiok says that the likely route will be simply making it so Ignite can't proc off periodic damage, which in theory shouldn't be a DPS loss at all, since Ignite will actually work at that point. If it does turn out to be a DPS loss, he says they can always adjust fire DPS in other ways.
So when can you expect the change? A future patch, apparently, since Bashiok says that this is the kind of thing they just don't like to hotfix, due to the unintended consequences it might have. At least it's in the pipeline.
Every week, Arcane Brilliance teleports you inside the wonderful world of mages and then hurls a Fireball in your face. Check out our recent Cataclysm 101 guide for new mages or our mage Thanksgiving spectacular. Until next week, keep the mage-train a-rollin'.